zizmor/docs/audits.md

description
Audit rules, examples, and remediations.

Audit Rules

This page documents each of the audits currently implemented in zizmor.

See each audit's section for its scope, behavior, and other information.

Legend:

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
The kind of audit ("Workflow" or "Action")	Links to vulnerable examples	Added to zizmor in this version	The audit works with --offline	The audit needs to be explicitly enabled via configuration or an API token	The audit supports custom configuration

anonymous-definition

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	N/A	v1.10.0	✅	❌	❌

Detects workflows or action definitions that lack a name: field.

GitHub explicitly allows workflows to omit the name: field, and allows (but doesn't document) the same for action definitions. When name: is omitted, the workflow or action is rendered anonymously in the GitHub Actions UI, making it harder to understand which definition is running.

!!! note

This is a `--pedantic` only audit, due to a lack of security impact.

Remediation

Add a name: field to your workflow or action.

=== "Before ⚠️"

```yaml title="anonymous-definition.yml" hl_lines="7"
on: push

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - run: echo "Hello!"
```

=== "After ✅"

```yaml title="anonymous-definition.yml" hl_lines="7-9"
name: Echo Test
on: push

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - run: echo "Hello!"
```

artipacked

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	artipacked.yml	v0.1.0	✅	✅	❌

Detects local filesystem git credential storage on GitHub Actions, as well as potential avenues for unintentional persistence of credentials in artifacts.

By default, using @actions/checkout causes a credential to be persisted in the checked-out repo's .git/config, so that subsequent git operations can be authenticated.

Subsequent steps may accidentally publicly persist .git/config, e.g. by including it in a publicly accessible artifact via @actions/upload-artifact.

However, even without this, persisting the credential in the .git/config is non-ideal unless actually needed.

Other resources:

• ArtiPACKED: Hacking Giants Through a Race Condition in GitHub Actions Artifacts

Remediation

Unless needed for git operations, @actions/checkout should be used with #!yaml persist-credentials: false.

If the persisted credential is needed, it should be made explicit with #!yaml persist-credentials: true.

=== "Before ⚠️"

```yaml title="artipacked.yml" hl_lines="7"
on: push

jobs:
  artipacked:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
```

=== "After ✅"

```yaml title="artipacked.yml" hl_lines="7-9"
on: push

jobs:
  artipacked:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          persist-credentials: false
```

bot-conditions

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	bot-conditions.yml	v1.2.0	✅	✅	❌

Detects potentially spoofable bot conditions.

Many workflows allow trustworthy bots (such as Dependabot) to bypass checks or otherwise perform privileged actions. This is often done with a github.actor check, e.g.:

if: github.actor == 'dependabot[bot]'

However, this condition is spoofable: github.actor refers to the last actor to perform an "action" on the triggering context, and not necessarily the actor actually causing the trigger. An attacker can take advantage of this discrepancy to create a PR where the HEAD commit has github.actor == 'dependabot[bot]' but the rest of the branch history contains attacker-controlled code, bypassing the actor check.

Other resources:

• GitHub Actions exploitations: Dependabot

Remediation

In general, checking a trigger's authenticity via github.actor is insufficient. Instead, most users should use github.event.pull_request.user.login or similar, since that context refers to the actor that created the Pull Request rather than the last one to modify it.

More generally, GitHub's documentation recommends not using pull_request_target for auto-merge workflows.

!!! example

=== "Before :warning:"

    ```yaml title="bot-conditions.yml" hl_lines="1 6"
    on: pull_request_target

    jobs:
      automerge:
        runs-on: ubuntu-latest
        if: github.actor == 'dependabot[bot]' && github.repository == github.event.pull_request.head.repo.full_name
        steps:
          - run: gh pr merge --auto --merge "$PR_URL"
            env:
              PR_URL: ${{ github.event.pull_request.html_url }}
              GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    ```

=== "After :white_check_mark:"

    ```yaml title="bot-conditions.yml" hl_lines="1 6"
    on: pull_request

    jobs:
      automerge:
        runs-on: ubuntu-latest
        if: github.event.pull_request.user.login == 'dependabot[bot]' && github.repository == github.event.pull_request.head.repo.full_name
        steps:
          - run: gh pr merge --auto --merge "$PR_URL"
            env:
              PR_URL: ${{ github.event.pull_request.html_url }}
              GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    ```

cache-poisoning

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	cache-poisoning.yml	v0.10.0	✅	✅	❌

Detects potential cache-poisoning scenarios in release workflows.

Caching and restoring build state is a process eased by utilities provided by GitHub, in particular @actions/cache and its "save" and "restore" sub-actions. In addition, many of the setup-like actions provided by GitHub come with built-in caching functionality, like @actions/setup-node, @actions/setup-java and others.

Furthermore, there are many examples of community-driven Actions with built-in caching functionality, like @ruby/setup-ruby, @astral-sh/setup-uv, @Swatinem/rust-cache. In general, most of them build on top of @actions/toolkit for the sake of easily integrate with GitHub cache server at Workflow runtime.

This vulnerability happens when release workflows leverage build state cached from previous workflow executions, in general on top of the aforementioned actions or similar ones. The publication of artifacts usually happens driven by trigger events like release or events with path filters like push (e.g. for tags).

In such scenarios, an attacker with access to a valid GITHUB_TOKEN can use it to poison the repository's GitHub Actions caches. That compounds with the default behavior of @actions/toolkit during cache restorations, allowing an attacker to retrieve payloads from poisoned cache entries, hence achieving code execution at Workflow runtime, potentially compromising ready-to-publish artifacts.

Other resources:

• The Monsters in Your Build Cache – GitHub Actions Cache Poisoning
• Cacheract: The Monster in your Build Cache

Remediation

In general, you should avoid using previously cached CI state within workflows intended to publish build artifacts:

• Remove cache-aware actions like @actions/cache from workflows that produce releases, or
• Disable cache-aware actions with an #!yaml if: condition based on the trigger at the step level, or
• Set an action-specific input to disable cache restoration when appropriate, such as lookup-only in @Swatinem/rust-cache.

dangerous-triggers

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	pull-request-target.yml	v0.1.0	✅	✅	❌

Detects fundamentally dangerous GitHub Actions workflow triggers.

Many of GitHub's workflow triggers are difficult to use securely. This audit checks for some of the biggest offenders:

• pull_request_target
• workflow_run

These triggers are dangerous because they run in the context of the target repository rather than the fork repository, while also being typically triggerable by the latter. This can lead to attacker controlled code execution or unexpected action runs with context controlled by a malicious fork.

Other resources:

• Keeping your GitHub Actions and workflows secure Part 1: Preventing pwn requests
• Vulnerable GitHub Actions Workflows Part 1: Privilege Escalation Inside Your CI/CD Pipeline

Remediation

The use of dangerous triggers can be difficult to remediate, since they don't always have an immediate replacement.

Replacing a dangerous trigger with a safer one (or keeping the dangerous trigger, but eliminating the risk of code execution) requires case-by-case consideration.

Some general pointers:

• Replace workflow_run triggers with workflow_call: this will require re-tooling the workflow to be a reusable workflow.

• Replace pull_request_target with pull_request, unless you absolutely need repository write permissions (e.g. to leave a comment or make other changes to the upstream repo).

  pull_request_target is only needed to perform privileged actions on pull requests from external forks. If you only expect pull requests from branches within the same repository, or if you are fine with some functionality not working for external pull requests, prefer pull_request.

• Automation for Dependabot pull requests can be implemented using pull_request, but requires setting dedicated Dependabot secrets and explicitly specifying needed permissions.

• Never run PR-controlled code in the context of a pull_request_target-triggered workflow.

• Avoid attacker-controllable flows into GITHUB_ENV in both workflow_run and pull_request_target workflows, since these can lead to arbitrary code execution.

• If you really have to use pull_request_target, consider adding a branch filter to only run the workflow for matching target branches. pull_request_target uses the workflow file of the target branch of the pull request, therefore restricting the target branches reduces the risk of a vulnerable pull_request_target in a stale or abandoned branch.

• If you have to use a dangerous trigger, consider adding a github.repository == ... check to only run for your repository but not in forks of your repository (in case the user has enabled Actions there). This avoids exposing forks to danger in case you fix a vulnerability in the workflow but the fork still contains an old vulnerable version.

excessive-permissions

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	excessive-permissions.yml	v0.1.0	✅	✅	❌

Detects excessive permissions in workflows, both at the workflow level and individual job levels.

Users frequently over-scope their workflow and job permissions, or set broad workflow-level permissions without realizing that all jobs inherit those permissions.

Furthermore, users often don't realize that the default GITHUB_TOKEN permissions can be very broad, meaning that workflows that don't configure any permissions at all can still provide excessive credentials to their individual jobs.

Remediation

In general, permissions should be declared as minimally as possible, and as close to their usage site as possible.

In practice, this means that workflows should almost always set #!yaml permissions: {} at the workflow level to disable all permissions by default, and then set specific job-level permissions as needed.

!!! tip

@GitHubSecurityLab/actions-permissions can help find the minimally required
permissions.

!!! example

=== "Before :warning:"

    ```yaml title="excessive-permissions.yml" hl_lines="8-9"
    on:
      release:
        types:
          - published

    name: release

    permissions:
      id-token: write # trusted publishing + attestations

    jobs:
      build:
        name: Build distributions 📦
        runs-on: ubuntu-latest
        steps:
          - # omitted for brevity

      publish:
        name: Publish Python 🐍 distributions 📦 to PyPI
        runs-on: ubuntu-latest
        needs: [build]

        steps:
          - name: Download distributions
            uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
            with:
              name: distributions
              path: dist/

          - name: publish
            uses: pypa/gh-action-pypi-publish@76f52bc884231f62b9a034ebfe128415bbaabdfc # v1.12.4
    ```

=== "After :white_check_mark:"

    ```yaml title="excessive-permissions.yml" hl_lines="8 21-22"
    on:
      release:
        types:
          - published

    name: release

    permissions: {}

    jobs:
      build:
        name: Build distributions 📦
        runs-on: ubuntu-latest
        steps:
          - # omitted for brevity

      publish:
        name: Publish Python 🐍 distributions 📦 to PyPI
        runs-on: ubuntu-latest
        needs: [build]
        permissions:
          id-token: write # trusted publishing + attestations

        steps:
          - name: Download distributions
            uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
            with:
              name: distributions
              path: dist/

          - name: publish
            uses: pypa/gh-action-pypi-publish@76f52bc884231f62b9a034ebfe128415bbaabdfc # v1.12.4
    ```

forbidden-uses

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	N/A	v1.6.0	✅	❌	✅

An opt-in audit for denylisting/allowlisting specific #!yaml uses: clauses. This is not enabled by default; you must configure it to use it.

!!! warning

This audit comes with several limitations that are important to understand:

* This audit is *opt-in*. You must configure it to use it; it
  **does nothing** by default.
* This audit (currently) operates on *repository* `#!yaml uses:` clauses,
  e.g. `#!yaml uses: actions/checkout@v4`. It does not operate on Docker
  `#!yaml uses:` clauses, e.g. `#!yaml uses: docker://ubuntu:24.04`. This limitation
  may be lifted in the future.
* This audit operates on `#!yaml uses:` clauses *as they appear* in the workflow
  and action files. In other words, in *cannot* detect
  [impostor commits](#impostor-commit) or indirect usage of actions
  via manual `git clone` and local path usage.
* This audit's configuration operates on patterns, just like
  [unpinned-uses](#unpinned-uses). That means that you can't (yet)
  define *exact* matches. For example, you can't forbid `actions/checkout@v4`,
  you have to forbid `actions/checkout`, which forbids all versions.

Configuration

rules.forbidden-uses.config.<allow|deny>

Type: list

The forbidden-uses audit operates on either an allowlist or denylist basis:

• In allowlist mode, only the listed #!yaml uses: patterns are allowed. All non-matching #!yaml uses: clauses result in a finding.

  Intended use case: only allowing "known good" actions to be used, and forbidding everything else.

• In denylist mode, only the listed #!yaml uses: patterns are disallowed. All matching #!yaml uses: clauses result in a finding.

  Intended use case: permitting all #!yaml uses: by default, but explicitly forbidding "known bad" actions.

Regardless of the mode, the patterns used are repository patterns. See Configuration - Repository patterns for details.

!!! example

The following configuration would allow only actions owned by
the @actions organization, plus any actions defined in @github/codeql-action:

```yaml title="zizmor.yml"
rules:
  forbidden-uses:
    config:
      allow:
        - actions/*
        - github/codeql-action/*
```

!!! example

The following would allow all actions except for those in the
@actions organization or defined in @github/codeql-action:

```yaml title="zizmor.yml"
rules:
  forbidden-uses:
    config:
      deny:
        - actions/*
        - github/codeql-action/*
```

Remediation

Either remove the offending #!yaml uses: clause or, if intended, add it to your configuration.

github-env

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	github-env.yml	v0.6.0	✅	✅	❌

Detects dangerous writes to the GITHUB_ENV and GITHUB_PATH environment variables.

When used in workflows with dangerous triggers (such as pull_request_target and workflow_run), GITHUB_ENV and GITHUB_PATH can be an arbitrary code execution risk:

• If the attacker is able to set arbitrary variables or variable contents via GITHUB_ENV, they may be able to set LD_PRELOAD or otherwise induce code execution implicitly within subsequent steps.
• If the attacker is able to add an arbitrary directory to the $PATH via GITHUB_PATH, they may be able to execute arbitrary code by shadowing ordinary system executables (such as ssh).

Other resources:

• GitHub Actions exploitation: environment manipulation
• GHSL-2024-177: Environment Variable injection in an Actions workflow of Litestar
• Google & Apache Found Vulnerable to GitHub Environment Injection
• Hacking with Environment Variables

Remediation

In general, you should avoid modifying GITHUB_ENV and GITHUB_PATH within sensitive workflows that are attacker-triggered, like pull_request_target.

If you absolutely must use GITHUB_ENV or GITHUB_PATH, avoid passing attacker-controlled values into either. Stick with literal strings and values computed solely from trusted sources.

If you need to pass state between steps, consider using GITHUB_OUTPUT instead.

hardcoded-container-credentials

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	hardcoded-credentials.yml	v0.1.0	✅	✅	❌

Detects Docker credentials (usernames and passwords) hardcoded in various places within workflows.

Remediation

Use encrypted secrets instead of hardcoded credentials.

!!! example

=== "Before :warning:"

    ```yaml title="hardcoded-container-credentials.yml" hl_lines="11 17"
    on:
      push:

    jobs:
      test:
        runs-on: ubuntu-latest
        container:
          image: fake.example.com/example
          credentials:
            username: user
            password: hackme
        services:
          service-1:
            image: fake.example.com/anotherexample
            credentials:
              username: user
              password: hackme
        steps:
          - run: echo 'hello!'
    ```

=== "After :white_check_mark:"

    ```yaml title="hardcoded-container-credentials.yml" hl_lines="11 17"
    on:
      push:

    jobs:
      test:
        runs-on: ubuntu-latest
        container:
          image: fake.example.com/example
          credentials:
            username: user
            password: ${{ secrets.REGISTRY_PASSWORD }}
        services:
          service-1:
            image: fake.example.com/anotherexample
            credentials:
              username: user
              password: ${{ secrets.REGISTRY_PASSWORD }} # (1)!
        steps:
          - run: echo 'hello!'
    ```

    1. This may or may not be the same credential as above, depending on your configuration.

impostor-commit

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	impostor-commit.yml	v0.1.0	❌	✅	❌

Detects commits within a repository action's network that are not present on the repository itself, also known as "impostor" commits.

GitHub represents a repository and its forks as a "network" of commits. This results in ambiguity about where a commit comes from: a commit that exists only in a fork can be referenced via its parent's owner/repo slug, and vice versa.

GitHub's network-of-forks design can be used to obscure a commit's true origin in a fully-pinned #!yaml uses: workflow reference. This can be used by an attacker to surreptitiously introduce a backdoored action into a victim's workflows(s).

A notable historical example of this is github/dmca@565ece486c, which appears to be on @github/dmca is but really on a fork (with an impersonated commit author).

Other resources:

• What the fork? Imposter commits in GitHub Actions and CI/CD

Remediation

Impostor commits are visually indistinguishable from normal best-practice hash-pinned actions.

Always carefully review external PRs that add or change hash-pinned actions by consulting the claimant repository and confirming that the commit actually exists within it.

The only remediation, once discovered, is to replace the impostor commit within an authentic commit (or an authentic tag/branch reference).

insecure-commands

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	insecure-commands.yml	v0.5.0	✅	✅	❌

Detects opt-in for executing insecure workflow commands.

Workflow commands (like ::set-env and ::add-path) were deprecated by GitHub in 2020 due to their inherent weaknesses (e.g., allowing any command with the ability to emit to stdout to inject environment variables and therefore obtain code execution).

However, users can explicitly re-enable them by setting the ACTIONS_ALLOW_UNSECURE_COMMANDS environment variable at the workflow, job, or step level.

Other resources:

• Semgrep audit

Remediation

In general, users should use GitHub Actions environment files (like GITHUB_PATH and GITHUB_OUTPUT) instead of using workflow commands.

!!! example

=== "Before :warning:"

    ```yaml title="insecure-commands" hl_lines="3"
    - name: Setup my-bin
      run: |
        echo "::add-path::$HOME/.local/my-bin"
      env:
        ACTIONS_ALLOW_UNSECURE_COMMANDS: true
    ```

=== "After :white_check_mark:"

    ```yaml title="insecure-commands" hl_lines="3"
    - name: Setup my-bin
      run: |
        echo "$HOME/.local/my-bin" >> "$GITHUB_PATH"
    ```

known-vulnerable-actions

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	known-vulnerable-actions.yml	v0.1.0	❌	✅	❌

Detects actions with known, publicly disclosed vulnerabilities that are tracked in the GitHub Advisories database. Examples of commonly disclosed vulnerabilities in GitHub Actions include credential disclosure and code injection via template injection.

Remediation

If the vulnerability is applicable to your use: upgrade to a fixed version of the action if one is available, or remove the action's usage entirely.

obfuscation

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	N/A	v1.7.0	✅	✅	❌

Checks for obfuscated usages of GitHub Actions features.

This audit primarily serves to "unstick" other audits, which may fail to detect functioning but obfuscated usages of GitHub Actions features.

This audit detects a variety of obfuscated usages, including:

• Obfuscated paths within #!yaml uses: clauses, including redundant / separators and uses of . or .. in path segments.
• Obfuscated GitHub expressions, including no-op patterns like fromJSON(toJSON(...)) and calls to format(...) where all arguments are literal values.

Remediation

Address the source of obfuscation by simplifying the expression, #!yaml uses: clause, or other obfuscated feature.

!!! example

=== "Before :warning:"

    ```yaml title="obfuscation.yml" hl_lines="8"
    jobs:
      build:
        runs-on: ubuntu-latest
        steps:
          - name: Checkout
            uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
            with:
              repository: ${{ format('{0}/{1}', 'octocat', 'hello-world') }}
    ```

=== "After :white_check_mark:"

    ```yaml title="obfuscation.yml" hl_lines="8"
    jobs:
      build:
        runs-on: ubuntu-latest
        steps:
          - name: Checkout
            uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
            with:
              repository: octocat/hello-world
    ```

overprovisioned-secrets

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	overprovisioned-secrets.yml	v1.3.0	✅	✅	❌

Detects excessive sharing of the secrets context.

Typically, users access the secrets context via its individual members:

env:
  SECRET_ONE: ${{ secrets.SECRET_ONE }}
  SECRET_TWO: ${{ secrets.SECRET_TWO }}

This allows the Actions runner to only expose the secrets actually used by the workflow to the job environment.

However, if the user instead accesses the entire secrets context:

env:
  SECRETS: ${{ toJson(secrets) }}

...then the entire secrets context is exposed to the runner, even if only a single secret is actually needed.

Remediation

In general, users should avoid loading the entire secrets context. Secrets should be accessed individually by name.

!!! example

=== "Before :warning:"

    ```yaml title="overprovisioned.yml" hl_lines="7"
    jobs:
      deploy:
        runs-on: ubuntu-latest
        steps:
          - run: ./deploy.sh
            env:
              SECRETS: ${{ toJSON(secrets) }}
    ```

=== "After :white_check_mark:"

    ```yaml title="overprovisioned.yml" hl_lines="7-8"
    jobs:
      deploy:
        runs-on: ubuntu-latest
        steps:
          - run: ./deploy.sh
            env:
              SECRET_ONE: ${{ secrets.SECRET_ONE }}
              SECRET_TWO: ${{ secrets.SECRET_TWO }}
    ```

ref-confusion

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	ref-confusion.yml	v0.1.0	❌	✅	❌

Detects actions that are pinned to confusable symbolic refs (i.e. branches or tags).

Like with impostor commits, actions that are used with a symbolic ref in their #!yaml uses: are subject to a degree of ambiguity: a ref like @v1 might refer to either a branch or tag ref.

An attacker can exploit this ambiguity to publish a branch or tag ref that takes precedence over a legitimate one, delivering a malicious action to pre-existing consumers of that action without having to modify those consumers.

Remediation

Switch to hash-pinned actions.

secrets-inherit

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	secrets-inherit.yml	v1.1.0	✅	✅	❌

Detects excessive secret inheritance between calling workflows and reusable (called) workflows.

Reusable workflows can be given secrets by their calling workflow either explicitly, or in a blanket fashion with #!yaml secrets: inherit. The latter should almost never be used, as it makes it violates the Principle of Least Authority and makes it impossible to determine which exact secrets a reusable workflow was executed with.

Remediation

In general, #!yaml secrets: inherit should be replaced with a #!yaml secrets: block that explicitly forwards each secret actually needed by the reusable workflow.

!!! example

=== "Before :warning:"

    ```yaml title="reusable.yml" hl_lines="4"
    jobs:
      pass-secrets-to-workflow:
        uses: ./.github/workflows/called-workflow.yml
        secrets: inherit
    ```

=== "After :white_check_mark:"

    ```yaml title="reusable.yml" hl_lines="4-6"
    jobs:
      pass-secrets-to-workflow:
        uses: ./.github/workflows/called-workflow.yml
        secrets:
          forward-me: ${{ secrets.forward-me }}
          me-too: ${{ secrets.me-too }}
    ```

self-hosted-runner

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	self-hosted.yml	v0.1.0	✅	❌	❌

!!! note

This is a `--pedantic` only audit, due to `zizmor`'s limited ability
to analyze runner configurations themselves. See #34 for more details.

Detects self-hosted runner usage within workflows.

GitHub supports self-hosted runners, which behave similarly to GitHub-hosted runners but use client-managed compute resources.

Self-hosted runners are very hard to secure by default, which is why GitHub does not recommend their use in public repositories.

Other resources:

• Self-hosted runner security

Remediation

In general, self-hosted runners should only be used on private repositories. Exposing self-hosted runners to potential public use is always a security risk.

In practice, there are many cases (such as custom host configurations) where a self-hosted runner is needed on a public repository. In these cases, there are steps you can take to minimize their risk:

1. Require manual approval on workflows for all external contributors. This can be configured at repository, workflow, or enterprise-wide levels. See GitHub's docs for more information.
2. Use only ephemeral ("just-in-time") runners. These runners are created just-in-time to perform one job and are destroyed immediately afterwards, making it harder (but not impossible) for an attacker to maintain persistence.

stale-action-refs

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	N/A	v1.7.0	❌	✅	❌

Checks for #!yaml uses: clauses which pin an action using a SHA reference, but where that reference does not point to a Git tag.

When using an action commit which is not a Git tag / release version, that commit might contain bugs or vulnerabilities which have not been publicly documented because they might have been fixed before the subsequent release. Additionally, because changelogs are usually only published for releases, it is difficult to tell which changes of the subsequent release the pinned commit includes.

!!! note

This is a `--pedantic` only audit because the detected situation is not
a vulnerability per se. But it might be worth investigating which commit
the SHA reference points to, and why not a SHA reference pointing to a
Git tag is used.

Some action repositories use a "rolling release branch" strategy where
all commits on a certain branch are considered releases. In such a case
findings of this audit can likely be ignored.

Remediation

Change the #!yaml uses: clause to pin the action using a SHA reference which points to a Git tag.

template-injection

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	template-injection.yml	v0.1.0	✅	✅	❌

Detects potential sources of code injection via template expansion.

GitHub Actions allows workflows to define template expansions, which occur within special ${{ ... }} delimiters. These expansions happen before workflow and job execution, meaning the expansion of a given expression appears verbatim in whatever context it was performed in.

Template expansions aren't syntax-aware, meaning that they can result in unintended shell injection vectors. This is especially true when they're used with attacker-controllable expression contexts, such as github.event.issue.title (which the attacker can fully control by supplying a new issue title).

Other resources:

• Keeping your GitHub Actions and workflows secure Part 2: Untrusted input

Remediation

The most common forms of template injection are in run: and similar code-execution blocks. In these cases, an inline template expansion can typically be replaced by an environment variable whose value comes from the expanded template.

This avoids the vulnerability, since variable expansion is subject to normal shell quoting/expansion rules.

!!! tip

To fully remediate the vulnerability, you **should not** use
`${{ env.VARNAME }}`, since that is still a template expansion.
Instead, you should use `${VARNAME}` to ensure that the shell *itself*
performs the variable expansion.

!!! tip

When switching to `${VARNAME}`, keep in mind that different shells have
different environment variable syntaxes. In particular, Powershell (the
default shell on Windows runners) uses `${env:VARNAME}`.

To avoid having to specialize your handling for different runners,
you can set `#!yaml shell: sh` or `#!yaml shell: bash`.

!!! example

=== "Before :warning:"

    ```yaml title="template-injection.yml" hl_lines="3"
    - name: Check title
      run: |
        title="${{ github.event.issue.title }}"
        if [[ ! $title =~ ^.*:\ .*$ ]]; then
          echo "Bad issue title"
          exit 1
        fi
    ```

=== "After :white_check_mark:"

    ```yaml title="template-injection.yml" hl_lines="3 8-9"
    - name: Check title
      run: |
        title="${ISSUE_TITLE}"
        if [[ ! $title =~ ^.*:\ .*$ ]]; then
          echo "Bad issue title"
          exit 1
        fi
      env:
        ISSUE_TITLE: ${{ github.event.issue.title }}
    ```

unpinned-images

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	unpinned-images.yml	v1.7.0	✅	✅	❌

Checks for container.image values where the image is not pinned by either a tag (other than latest) or SHA256.

When image references are unpinned or are pinned to a mutable tag, the workflow is at risk because the image used will be unpredictable over time. Changes made to the OCI registry used to source the image may result in untrusted images gaining access to your workflow.

This can be a security risk:

1. Registries may not consistently enforce immutable image tags
2. Completely unpinned images can be changed at any time by the OCI registry.

By default, this audit applies the following policy:

• Regular findings are created for all image references missing a tag

  container:
    image: foo/bar
  

  or using the latest tag:

  container:
    image: foo/bar:latest
  

• Pedantic findings are created for all image references using a tag (!= latest) rather than SHA256 hash.

  container:
    image: foo/bar:not-a-sha256
  

Other resources:

• Aqua: The Challenges of Uniquely Identifying Your Images
• GitHub: Safeguard your containers with new container signing capability in GitHub Actions

Remediation

Pin the #!yaml container.image: value to a specific SHA256 image registry hash.

Many popular registries will display the hash value in their web console or you can use the command line to determine the hash of an image you have previously pulled by running #!bash docker inspect redis:7.4.3 --format='{{.RepoDigests}}'.

!!! example

=== "Before :warning:"

    ```yaml title="unpinned-images.yml" hl_lines="7-8"
    name: unpinned-images
    on: [push]

    jobs:
      unpinned-image:
        runs-on: ubuntu-latest
        container:
          image: fake.example.com/example
        steps:
          - run: "echo unpinned container!"
    ```

=== "After :white_check_mark:"

    ```yaml title="unpinned-images.yml" hl_lines="7-8"
    name: unpinned-images
    on: [push]

    jobs:
      unpinned-image:
        runs-on: ubuntu-latest
        container:
          image: fake.example.com/example@sha256:01ba4719c80b6fe911b091a7c05124b64eeece964e09c058ef8f9805daca546b
        steps:
          - run: "echo pinned container!"
    ```

unpinned-uses

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	unpinned.yml	v0.4.0	✅	✅	✅

Detects "unpinned" #!yaml uses: clauses.

When a #!yaml uses: clause is not pinned by branch, tag, or SHA reference, GitHub Actions will use the latest commit on the referenced repository's default branch (or, in the case of Docker actions, the :latest tag).

Similarly, if a #!yaml uses: clause is pinned via branch or tag (i.e. a "symbolic reference") instead of a SHA reference, GitHub Actions will use whatever commit is at the tip of that branch or tag. GitHub does not have immutable branches or tags, meaning that the action can change without the symbolic reference changing.

This can be a security risk:

1. Completely unpinned actions can be changed at any time by the upstream repository.
2. Tag- or branch-pinned actions can be changed by the upstream repository, either by force-pushing over the tag or updating the branch.

If the upstream repository is trusted, then symbolic references are often suitable. However, if the upstream repository is not trusted, then actions should be pinned by SHA reference.

By default, this audit applies the following policy:

• Official GitHub actions namespaces can be pinned by branch or tag. In other words, actions/checkout@v4 is acceptable, but actions/checkout is not.
• All other actions must be pinned by SHA reference.

This audit can be configured with a custom set of rules, e.g. to allow symbolic references for trusted repositories or entire namespaces (e.g. foocorp/*). See unpinned-uses - Configuration for details.

Specifying a configuration overrides the default policy above.

Other resources:

• Palo Alto Networks Unit42: tj-actions/changed-files incident

Configuration

!!! note

`unpinned-uses` is configurable in `v1.6.0` and later.

If the default unpinned-uses rules isn't suitable for your use case, you can override it with a custom set of policies.

rules.unpinned-uses.config.policies

Type: object

The rules.unpinned-uses.config.policies object defines your unpinned-uses policies.

Each member is a #!yaml pattern: policy rule, where pattern describes which #!yaml uses: clauses to match and policy describes how to treat them.

The pattern is a repository pattern; see Configuration - Repository patterns for details.

The valid policies are:

• hash-pin: any #!yaml uses: clauses that match the associated pattern must be fully pinned by SHA reference.
• ref-pin: any #!yaml uses: clauses that match the associated pattern must be pinned either symbolic or SHA reference.
• any: no pinning is required for any #!yaml uses: clauses that match the associated pattern.

If a #!yaml uses: clauses matches multiple rules, the most specific one is used regardless of definition order.

!!! example

The following configuration contains two rules that could match
@actions/checkout, but the first one is more specific and therefore gets applied:

```yaml title="zizmor.yml"
rules:
  unpinned-uses:
    config:
      policies:
        actions/checkout: hash-pin
        actions/*: ref-pin
```

In plain English, this policy set says "anything that `#!yaml uses: actions/*` must
be at least ref-pinned, but @actions/checkout in particular must be hash-pinned."

!!! example

```yaml title="zizmor.yml"
rules:
  unpinned-uses:
    config:
      policies:
        "example/*": hash-pin
        "*": ref-pin
```

In plain English, this policy set says "anything that `#!yaml uses: example/*` must
be hash-pinned, and anything else must be at least ref-pinned."

!!! important

If a `#!yaml uses:` clause does not match any rules, then an implicit
`#!yaml "*": hash-pin` rule is applied. Users can override this implicit rule
by adding their own `*` rule or a more precise rule, e.g.
`#!yaml "github/*": ref-pin` for actions under the @github organization.

Remediation

!!! tip

There are several third-party tools that can automatically hash-pin
your workflows and actions for you:

- :simple-go: @suzuki-shunsuke/pinact: supports updating and hash-pinning
  workflows, actions, and arbitrary inputs.
- :simple-python: @davidism/gha-update: supports updating and hash-pinning
  workflow definitions.
- :simple-go: @stacklok/frizbee: supports hash-pinning (but not updating)
  workflow definitions.

    See also stacklok/frizbee#184 for current usage caveats.

For repository actions (like @actions/checkout): add a branch, tag, or SHA reference.

For Docker actions (like docker://ubuntu): add an appropriate :{version} suffix.

!!! example

=== "Before :warning:"

    ```yaml title="unpinned-uses.yml" hl_lines="8 12"
    name: unpinned-uses
    on: [push]

    jobs:
      unpinned-uses:
          runs-on: ubuntu-latest
          steps:
          - uses: actions/checkout
            with:
            persist-credentials: false

          - uses: docker://ubuntu
            with:
            entrypoint: /bin/echo
            args: hello!
    ```

=== "After :white_check_mark:"

    ```yaml title="unpinned-uses.yml" hl_lines="8 12"
    name: unpinned-uses
    on: [push]

    jobs:
      unpinned-uses:
          runs-on: ubuntu-latest
          steps:
          - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
            with:
            persist-credentials: false

          - uses: docker://ubuntu:24.04
            with:
            entrypoint: /bin/echo
            args: hello!
    ```

unredacted-secrets

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow, Action	unredacted-secrets.yml	v1.4.0	✅	✅	❌

Detects potential secret leakage via redaction failures.

Typically, users access the secrets context via its individual members:

env:
  PASSWORD: ${{ secrets.PASSWORD }}

This allows the Actions runner to redact the secret values from the job logs, as it knows the exact string value of each secret.

However, if the user instead treats the secret as a structured value, e.g. JSON:

env:
  PASSWORD: ${{ fromJSON(secrets.MY_SECRET).password }}

...then the password field is not redacted, as the runner does not treat arbitrary substrings of secrets as secret values.

Other resources:

• Using secrets in GitHub Actions

Remediation

In general, users should avoid treating secrets as structured values. For example, instead of storing a JSON object in a secret, store the individual fields as separate secrets.

!!! example

=== "Before :warning:"

    ```yaml title="unredacted-secrets.yml" hl_lines="7-8"
    jobs:
      deploy:
        runs-on: ubuntu-latest
        steps:
          - run: ./deploy.sh
            env:
              USERNAME: ${{ fromJSON(secrets.MY_SECRET).username }}
              PASSWORD: ${{ fromJSON(secrets.MY_SECRET).password }}
    ```

=== "After :white_check_mark:"

    ```yaml title="unredacted-secrets.yml" hl_lines="7-8"
    jobs:
      deploy:
        runs-on: ubuntu-latest
        steps:
          - run: ./deploy.sh
            env:
              USERNAME: ${{ secrets.MY_SECRET_USERNAME }}
              PASSWORD: ${{ secrets.MY_SECRET_PASSWORD }}
    ```

unsound-contains

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	unsound-contains.yml	v1.7.0	✅	✅	❌

Detects conditions that use the contains() function in a way that can be bypassed.

Some workflows use contains() to check if a context variable is in a list of values (e.g., if the the push that triggered the job targeted a certain branch), and then bypass checks or otherwise perform privileged actions:

if: contains('refs/heads/main refs/heads/develop', github.ref)

However, this condition will not only evaluate to true if either refs/heads/main or refs/heads/develop is passed, but also for substrings of those values. For example, if someone pushes to a branch named mai, then github.ref would contain the string refs/heads/mai and the job would also execute.

Remediation

To check if a value is contained in a list of strings, the first argument to contains() should be an actual list, not a string. This can be done by using the fromJSON() function:

if: contains(fromJSON('["refs/heads/main", "refs/heads/develop"]'), github.ref)

Alternatively, it's possible to check for equality individually and combine the results using the logical "or" operator:

if: github.ref == "refs/heads/main" || github.ref == "refs/heads/develop"

Other resources:

• GitHub Docs: Evaluate expressions in workflows and actions - Example matching an array of strings

!!! example

=== "Before :warning:"

    ```yaml title="unsound-contains.yml" hl_lines="9 10"
    on: push

    jobs:
      tf-deploy:
        runs-on: ubuntu-latest
        steps:
          - run: terraform init -input=false
          - run: terraform plan -out=tfplan -input=false
          - run: terraform apply -input=false tfplan
            if: contains('refs/heads/main refs/heads/develop', github.ref)
    ```

=== "After :white_check_mark:"

    ```yaml title="unsound-contains.yml" hl_lines="9 10"
    on: push

    jobs:
      tf-deploy:
        runs-on: ubuntu-latest
        steps:
          - run: terraform init -input=false
          - run: terraform plan -out=tfplan -input=false
          - run: terraform apply -input=false tfplan
            if: contains(fromJSON('["refs/heads/main", "refs/heads/develop"]'), github.ref)
    ```

use-trusted-publishing

Type	Examples	Introduced in	Works offline	Enabled by default	Configurable
Workflow	pypi-manual-credential.yml	v0.1.0	✅	✅	❌

Detects packaging workflows that could use Trusted Publishing.

Some packaging ecosystems/indices (like PyPI and RubyGems) support "Trusted Publishing," which is an OIDC-based "tokenless" authentication mechanism for uploading to the index from within a CI/CD workflow.

This "tokenless" flow has significant security benefits over a traditional manually configured API token, and should be preferred wherever supported and possible.

Other resources:

• Trusted Publishers for All Package Repositories
• Publishing to PyPI with a Trusted Publisher
• Trusted Publishing - RubyGems Guides
• Trusted publishing: a new benchmark for packaging security

Remediation

In general, enabling Trusted Publishing requires a one-time change to your package's configuration on its associated index (e.g. PyPI or RubyGems).

Once your Trusted Publisher is registered, see @pypa/gh-action-pypi-publish or @rubygems/release-gem for canonical examples of using it.