diff --git a/crates/ruff_linter/resources/test/fixtures/ruff/RUF009.py b/crates/ruff_linter/resources/test/fixtures/ruff/RUF009.py
index b8c76574c2..511d20b8ac 100644
--- a/crates/ruff_linter/resources/test/fixtures/ruff/RUF009.py
+++ b/crates/ruff_linter/resources/test/fixtures/ruff/RUF009.py
@@ -125,4 +125,13 @@ class D:
 
 @dataclass
 class E:
-    c: C = C()
\ No newline at end of file
+    c: C = C()
+
+# https://github.com/astral-sh/ruff/issues/20266
+@dataclass(frozen=True)
+class C:
+    @dataclass(frozen=True)
+    class D:
+        foo: int = 1
+
+    d: D = D() # OK
\ No newline at end of file
diff --git a/crates/ruff_linter/src/checkers/ast/analyze/deferred_scopes.rs b/crates/ruff_linter/src/checkers/ast/analyze/deferred_scopes.rs
index 2cf6ec15bb..26cf918731 100644
--- a/crates/ruff_linter/src/checkers/ast/analyze/deferred_scopes.rs
+++ b/crates/ruff_linter/src/checkers/ast/analyze/deferred_scopes.rs
@@ -134,7 +134,7 @@ pub(crate) fn deferred_scopes(checker: &Checker) {
                 );
             }
             if checker.is_rule_enabled(Rule::FunctionCallInDataclassDefaultArgument) {
-                ruff::rules::function_call_in_dataclass_default(checker, class_def);
+                ruff::rules::function_call_in_dataclass_default(checker, class_def, scope_id);
             }
             if checker.is_rule_enabled(Rule::MutableClassDefault) {
                 ruff::rules::mutable_class_default(checker, class_def);
diff --git a/crates/ruff_linter/src/rules/ruff/rules/function_call_in_dataclass_default.rs b/crates/ruff_linter/src/rules/ruff/rules/function_call_in_dataclass_default.rs
index 2e1045ba76..26c4c5d657 100644
--- a/crates/ruff_linter/src/rules/ruff/rules/function_call_in_dataclass_default.rs
+++ b/crates/ruff_linter/src/rules/ruff/rules/function_call_in_dataclass_default.rs
@@ -2,10 +2,10 @@ use ruff_python_ast::{self as ast, Expr, Stmt};
 
 use ruff_macros::{ViolationMetadata, derive_message_formats};
 use ruff_python_ast::name::{QualifiedName, UnqualifiedName};
-use ruff_python_semantic::SemanticModel;
 use ruff_python_semantic::analyze::typing::{
     is_immutable_annotation, is_immutable_func, is_immutable_newtype_call,
 };
+use ruff_python_semantic::{ScopeId, SemanticModel};
 use ruff_text_size::Ranged;
 
 use crate::Violation;
@@ -77,7 +77,11 @@ impl Violation for FunctionCallInDataclassDefaultArgument {
 }
 
 /// RUF009
-pub(crate) fn function_call_in_dataclass_default(checker: &Checker, class_def: &ast::StmtClassDef) {
+pub(crate) fn function_call_in_dataclass_default(
+    checker: &Checker,
+    class_def: &ast::StmtClassDef,
+    scope_id: ScopeId,
+) {
     let semantic = checker.semantic();
 
     let Some((dataclass_kind, _)) = dataclass_kind(class_def, semantic) else {
@@ -144,7 +148,7 @@ pub(crate) fn function_call_in_dataclass_default(checker: &Checker, class_def: &
             || func.as_name_expr().is_some_and(|name| {
                 is_immutable_newtype_call(name, checker.semantic(), &extend_immutable_calls)
             })
-            || is_frozen_dataclass_instantiation(func, semantic)
+            || is_frozen_dataclass_instantiation(func, semantic, scope_id)
         {
             continue;
         }
@@ -165,16 +169,22 @@ fn any_annotated(class_body: &[Stmt]) -> bool {
 
 /// Checks that the passed function is an instantiation of the class,
 /// retrieves the ``StmtClassDef`` and verifies that it is a frozen dataclass
-fn is_frozen_dataclass_instantiation(func: &Expr, semantic: &SemanticModel) -> bool {
-    semantic.lookup_attribute(func).is_some_and(|id| {
-        let binding = &semantic.binding(id);
-        let Some(Stmt::ClassDef(class_def)) = binding.statement(semantic) else {
-            return false;
-        };
+fn is_frozen_dataclass_instantiation(
+    func: &Expr,
+    semantic: &SemanticModel,
+    scope_id: ScopeId,
+) -> bool {
+    semantic
+        .lookup_attribute_in_scope(func, scope_id)
+        .is_some_and(|id| {
+            let binding = &semantic.binding(id);
+            let Some(Stmt::ClassDef(class_def)) = binding.statement(semantic) else {
+                return false;
+            };
 
-        let Some((_, dataclass_decorator)) = dataclass_kind(class_def, semantic) else {
-            return false;
-        };
-        is_frozen_dataclass(dataclass_decorator, semantic)
-    })
+            let Some((_, dataclass_decorator)) = dataclass_kind(class_def, semantic) else {
+                return false;
+            };
+            is_frozen_dataclass(dataclass_decorator, semantic)
+        })
 }
diff --git a/crates/ruff_python_semantic/src/model.rs b/crates/ruff_python_semantic/src/model.rs
index 16d57622cc..b8de310a36 100644
--- a/crates/ruff_python_semantic/src/model.rs
+++ b/crates/ruff_python_semantic/src/model.rs
@@ -859,11 +859,17 @@ impl<'a> SemanticModel<'a> {
     /// associated with `Class`, then the `BindingKind::FunctionDefinition` associated with
     /// `Class.method`.
     pub fn lookup_attribute(&self, value: &Expr) -> Option<BindingId> {
+        self.lookup_attribute_in_scope(value, self.scope_id)
+    }
+
+    /// Lookup a qualified attribute in the certain scope.
+    pub fn lookup_attribute_in_scope(&self, value: &Expr, scope_id: ScopeId) -> Option<BindingId> {
         let unqualified_name = UnqualifiedName::from_expr(value)?;
 
         // Find the symbol in the current scope.
         let (symbol, attribute) = unqualified_name.segments().split_first()?;
-        let mut binding_id = self.lookup_symbol(symbol)?;
+        let mut binding_id =
+            self.lookup_symbol_in_scope(symbol, scope_id, self.in_forward_reference())?;
 
         // Recursively resolve class attributes, e.g., `foo.bar.baz` in.
         let mut tail = attribute;