Executive brief
A security vulnerability in Woodpecker CI, a popular continuous integration tool, allows an authenticated agent to impersonate other agents on the same server. By spoofing identification data, a malicious agent could potentially interfere with build processes or access data belonging to other tenants. This could lead to unauthorized modifications of software builds and disrupt development operations.
Technical details
A vulnerability exists in Woodpecker CI's gRPC communication layer (CWE-290, CWE-639) where the server fails to properly enforce the identity verified by a JWT token. While the server correctly validates the token, it subsequently discards the verified identity in favor of a client-supplied 'agent_id' value found in the gRPC metadata. An attacker with valid agent credentials can exploit this to impersonate any other agent on the same server. The issue is fixed in version 3.14.1. A workaround involves disabling user agent registration via the WOODPECKER_DISABLE_USER_AGENT_REGISTRATION environment variable.
Affected products
- Woodpecker CI woodpecker-ci/woodpecker/v3 >= 3.0.0, < 3.14.1
Timeline
- 2026-06-03: disclosed: Vulnerability reported to Woodpecker CI
- 2026-06-18: advisory: NVD publication date
- 2026-07-14: patched: GitHub Advisory published and reviewed
References
- https://api.github.com/users/shivamkumarcyber
- https://github.com/shivamkumarcyber
- https://api.github.com/users/shivamkumarcyber/gists%7B/gist_id%7D
- https://api.github.com/users/shivamkumarcyber/repos
- https://avatars.githubusercontent.com/u/104438732?v=4
- https://api.github.com/users/shivamkumarcyber/events%7B/privacy%7D