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🛡️ Sentinel: [CRITICAL] Fix Arbitrary Code Execution in Type Resolution Eval#351

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🛡️ Sentinel: [CRITICAL] Fix Arbitrary Code Execution in Type Resolution Eval#351
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fix/sentinel-arbitrary-code-execution-2303909245205650646

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@bashandbone bashandbone commented May 14, 2026

The _safe_eval_type method in src/codeweaver/core/di/container.py was found to have a severe Arbitrary Code Execution vulnerability.

The AST pass allowed ast.Call nodes so that Pydantic fields or Dependency Injection annotations (e.g. Depends()) could be evaluated via eval(). Because eval is called with a globalns environment (which can contain local functions and imports), an attacker could execute arbitrary functions by supplying an unexpected type string (like "ExploitClass().execute()").

Fix

The TypeValidator.generic_visit method was updated:

  • It now enforces a strict whitelist of known-safe functions that can be called during type evaluation (Depends, depends, Field, PrivateAttr).
  • It enforces that node.func must be an ast.Name to prevent dot notation attacks (e.g. os.system).

Tests have been run, confirming the exploit is prevented, while DI container functions remain fully operational. Learnings have been documented in .jules/sentinel.md.


PR created automatically by Jules for task 2303909245205650646 started by @bashandbone

Summary by Sourcery

Harden type resolution evaluation in the DI container to prevent arbitrary code execution and document the related security incident in Sentinel notes.

Bug Fixes:

  • Prevent arbitrary code execution during type resolution by restricting evaluated function calls to a small whitelist of safe dependency-related helpers.

Documentation:

  • Add a Sentinel security incident entry describing the arbitrary code execution vulnerability in type resolution and the mitigation via strict AST call whitelisting.

The `_safe_eval_type` function in `src/codeweaver/core/di/container.py` validates type strings before calling `eval()` using an AST pass. It permitted `ast.Call` nodes to allow for annotations like `Annotated[T, Depends(...)]`. However, this could lead to arbitrary code execution by an attacker exploiting functions in the `globalns` passed to the eval environment (e.g., executing `os.system(...)`).

This commit updates the `TypeValidator` to enforce a strict allowlist of functions within `ast.Call` nodes (`Depends`, `depends`, `Field`, `PrivateAttr`), and ensures `node.func` is always an `ast.Name` to prevent object attribute access (dot notation) attacks.

Co-authored-by: bashandbone <89049923+bashandbone@users.noreply.github.com>
Copilot AI review requested due to automatic review settings May 14, 2026 18:51
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sourcery-ai Bot commented May 14, 2026

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Tightens the AST-based type evaluation in the DI container to only allow a small, explicit set of safe function calls during eval, preventing arbitrary code execution, and records the incident and mitigation details in the Sentinel security log.

File-Level Changes

Change Details Files
Harden AST validation for type resolution eval to prevent arbitrary code execution while preserving supported DI annotations.
  • Extend TypeValidator.generic_visit to detect ast.Call nodes during type parsing.
  • Introduce a small whitelist of allowed callable identifiers used in type annotations (Depends, depends, Field, PrivateAttr).
  • Require that the call target be a simple ast.Name (rejecting attributes and other complex callables) and raise TypeError when encountering disallowed calls.
  • Keep the existing recursive AST traversal via super().generic_visit(node) so other validations still run.
src/codeweaver/core/di/container.py
Document the new arbitrary code execution vulnerability and its remediation in the Sentinel security history.
  • Add a new Sentinel entry describing the ACE vulnerability in _safe_eval_type within the DI container.
  • Record the key learning that AST validation must include strict identifier whitelisting for calls.
  • Document the preventive measure of whitelisting only expected DI-related call identifiers in ast.Call nodes.
.jules/sentinel.md

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Hey - I've left some high level feedback:

  • Consider extracting the allowed_funcs set to a module- or class-level constant so the whitelist is defined in a single place and easier to audit or extend in future changes.
Prompt for AI Agents
Please address the comments from this code review:

## Overall Comments
- Consider extracting the `allowed_funcs` set to a module- or class-level constant so the whitelist is defined in a single place and easier to audit or extend in future changes.

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Pull request overview

This PR addresses a critical arbitrary code execution vulnerability in _safe_eval_type within the DI container. The AST validator previously allowed any ast.Call node, enabling arbitrary function execution via eval() since the call could resolve to functions in the supplied globalns. The fix restricts ast.Call to a small whitelist of known type-annotation helpers and forbids attribute-based calls.

Changes:

  • Add a whitelist (Depends, depends, Field, PrivateAttr) for ast.Call function names in TypeValidator.generic_visit.
  • Require node.func to be an ast.Name (rejects obj.method() style calls).
  • Document the vulnerability and prevention in .jules/sentinel.md.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File Description
src/codeweaver/core/di/container.py Enforces strict call whitelist in the AST type validator to block arbitrary code execution.
.jules/sentinel.md Adds postmortem entry documenting the vulnerability and mitigation.

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