Summary

Woodpecker gRPC agent_id metadata can be spoofed- cross-tenant agent impersonation

Advisory details

Impact

A vulnerability in Woodpecker CI's gRPC layer allowed any authenticated agent to impersonate any other agent on the same server by injecting a forged agent_id value into outgoing gRPC metadata. The server correctly verified the JWT token but then discarded the verified agent identity in favor of the client-supplied value.

Patches

Direct patch: https://github.com/woodpecker-ci/woodpecker/pull/6567 Later proper fix: https://github.com/woodpecker-ci/woodpecker/pull/6569

Workarounds

Disable org agents (WOODPECKER_DISABLE_USER_AGENT_REGISTRATION=true) and delete existing ones

Resources

Public ref: https://github.com/woodpecker-ci/woodpecker/issues/6541 Private com: https://github.com/woodpecker-ci/woodpecker-security/issues/21

References