GHSA-qf34-295c-26v8 Woodpecker: Privilege escalation via unrestricted serviceAccountName in the Kubernetes backend

• Go go.woodpecker-ci.org/woodpecker/v3: < 3.16.0 → fixed in 3.16.0 • Go github.com/woodpecker-ci/woodpecker: >= 1.0.0, <= 1.0.4 (no fix yet) • Go go.woodpecker-ci.org/woodpecker/v2: <= 2.8.3 (no fix yet)

Impact A privilege escalation vulnerability affects Woodpecker instances using the Kubernetes backend. The pipeline option `backend_options.kubernetes.serviceAccountName` was passed directly to the pod spec without any admin gating. Who is impacted: any operator running the Kubernetes backend. Any user with Push permission on a connected repository can run pipeline pods under an arbitrary ServiceAccount in the pipeline namespace, gaining that account's RBAC permissions. If a privileged ServiceAccount is reachable in that namespace, this can lead to secret exfiltration (database credentials, API keys, TLS certs) and full cluster takeover. Patches https://github.com/woodpecker-ci/woodpecker/pull/6792 Workarounds Operators who cannot upgrade immediately can mitigate by any of: • Restrict Push access on repositories connected to the Kubernetes-backed instance to trusted users only. • Harden the pipeline namespace: ensure no privileged ServiceAccount exists or is bound in the namespace where pipeline pods run; keep the `default` ServiceAccount minimally privileged. • Disable ServiceAccount token automounting for ServiceAccounts that should not be used by pipelines. • Enforce an admission policy (e.g. OPA/Gatekeeper, Kyverno, or a ValidatingAdmissionPolicy) that rejects pipeline pods setting an unexpected `serviceAccountName`. • Use a dedicated, isolated namespace per org/instance with no sensitive RBAC bindings. Resources • Vulnerable option introduced in commit `609ba481b5e912f59aaae8ca7bc22b44523c5e37` • Affected versions: `v1.0.0` through `v3.15.0` • Source: `pipeline/backend/kubernetes/backend_options.go` (field `ServiceAccountName`), `pipeline/backend/kubernetes/pod.go` (assigned to pod spec with no gating)