utcp-http before 1.1.4 fails to validate the OAuth2 tokenUrl field from remote OpenAPI specifications, allowing attackers to redirect credential submission to arbitrary endpoints. When a victim registers an attacker-controlled OpenAPI spec and invokes a generated OAuth2-protected tool, the library POSTs the victims client_id and client_secret to the attacker-supplied token endpoint without URL validation.
Weakness
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
Related Attack Patterns
References
- https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-8cp3-qxj6-px34
- https://www.vulncheck.com/advisories/utcp-http-before-1.1.4-oauth2-tokenurl-trust-boundary-bypass
- https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-8cp3-qxj6-px34