🛡️ Sentinel: [CRITICAL] Fix arbitrary code execution in AST eval via unrestricted ast.Call

.jules/sentinel.md

@@ -4,3 +4,8 @@
 **Vulnerability:** Found an unused `_attempt_import` function in `src/codeweaver/server/mcp/server.py` that dynamically imports a module directly from unvalidated configuration (`import_module(mw.rsplit(".", 1)[0])`), leading to potential arbitrary code execution.
 **Learning:** Functions that perform dynamic imports should not be left around in the codebase if they are unused, especially if they are designed to take unvalidated strings as input.
 **Prevention:** Avoid dynamic imports based on configuration or inputs without strict whitelisting. Use tools like `semgrep` with python security rules to actively catch these patterns.
+
+## 2025-05-18 - Restrict AST calls to prevent ACE in type hints
+**Vulnerability:** Discovered that dynamic type evaluation in `src/codeweaver/core/di/container.py` using safe AST traversal allowed generic `ast.Call` nodes, enabling Arbitrary Code Execution (ACE) via the module's global namespace.
+**Learning:** Permitting arbitrary functions to be called during AST evaluation of unvalidated or dynamic strings can lead to ACE vulnerabilities even when standard Python `eval` limitations are partially enforced.
+**Prevention:** Strictly whitelist allowed functions (e.g., `Depends`, `Field`, `Parameter`) when validating AST trees and explicitly reject any `ast.Call` nodes executing unrecognized functions.

src/codeweaver/core/di/container.py

@@ -84,7 +84,7 @@ def __init__(self) -> None:
         self._request_cache: dict[Any, Any] = {}  # Keys can be types or callables
         self._providers_loaded: bool = False  # Track if auto-discovery has run
 
-    def _safe_eval_type(self, type_str: str, globalns: dict[str, Any]) -> Any | None:
+    def _safe_eval_type(self, type_str: str, globalns: dict[str, Any]) -> Any | None: # noqa: C901
         """Safely evaluate a type string using AST validation.
 
         Parses the type string into an AST, validates that it contains only safe
@@ -136,6 +136,20 @@ def generic_visit(self, node: ast.AST) -> None:
                 if isinstance(node, ast.Attribute) and node.attr.startswith("__"):
                     raise TypeError(f"Forbidden dunder attribute: {node.attr}")
 
+                # Restrict AST calls to prevent Arbitrary Code Execution vulnerabilities
+                # when safely evaluating type hint strings using safe eval patterns.
+                # Allow strictly whitelisted functions only.
+                if isinstance(node, ast.Call):
+                    allowed_funcs = {"Depends", "depends", "Field", "PrivateAttr", "Tag", "Parameter"}
+                    func_name = None
+                    if isinstance(node.func, ast.Name):
+                        func_name = node.func.id
+                    elif isinstance(node.func, ast.Attribute):
+                        func_name = node.func.attr
+
+                    if func_name not in allowed_funcs:
+                        raise TypeError(f"Forbidden function call in type string: {func_name}")
+
                 super().generic_visit(node)
 
         try: