T05 · Unauthorized Access and Privilege Escalation
Error
- Location
- SKILL.md:74
- Finding
- Authentication Dependency Stub May Permit Unauthorized Access## Vulnerability Details **File Location**: `SKILL.md`, lines 74-76 **Vulnerability Type**: Authentication and authorization bypass **Risk Level**: High **Vulnerable Code**: ```python async def get_current_user_id(): """Get current user ID""" return None ``` ### Technical Analysis The Skill recommends implementing an authentication dependency that neither validates credentials nor rejects unauthenticated requests. It always returns `None`. In a FastAPI application, dependencies named `get_current_user_id` are commonly used as security boundaries for protected endpoints. Returning `None` rather than raising an authentication exception can cause downstream handlers to process an unauthenticated request. Exploitability depends on how callers handle the returned value, but endpoints that interpret `None` as a default user, omit an explicit null check, or rely solely on successful dependency execution may become accessible without valid credentials. ### Attack Path 1. An operator follows the troubleshooting instructions and adds the documented dependency. 2. A protected endpoint declares `get_current_user_id` as its authentication dependency. 3. An attacker submits a request without a token, or with an invalid token. 4. The dependency performs no credential verification and returns `None` instead of an HTTP 401 or 403 response. 5. If the endpoint does not independently reject `None`, it continues processing the unauthenticated request. 6. The attacker may access functionality or data that was intended to require authentication. ### Impact Assessment The maximum impact depends on the authorization logic of affected endpoints. Potential consequences include anonymous access to protected operations, disclosure of user or business data, unauthorized state changes, and incorrect user scoping. If privileged endpoints trust this dependency without additional checks, the issue could cross application-level privilege boun ...[truncated 7 chars]
- Remediation
- ## Remediation Suggestions - Remove the placeholder implementation from deployment guidance. - Validate the request credential with the application's established token-verification function. - Return a strongly typed authenticated user identifier only after verifying token signature, expiration, issuer, audience, and required claims. - Raise `HTTPException(status_code=401)` for missing or invalid credentials and `HTTPException(status_code=403)` for insufficient permissions. - Ensure every protected endpoint applies explicit authorization checks after authentication. - Add tests confirming that missing, malformed, expired, and forged tokens are rejected and that users cannot access another user's resources. - Clearly label any illustrative placeholder as non-production code if it must remain in the documentation.