CVE-2026-66877: Gitea fork workflow approval bypass through concurrency cancellation

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-14 · updated 2026-10-15
Weakness: CWE-284

Description

Gitea enforces first-time fork contributor approval by blocking jobs, but some job transition and dispatch paths do not re-check the run's approval requirement. A separate run sharing a job-level concurrency group can cancel a pending job and cause its blocked sibling jobs to be re-emitted and dispatched without approval. This allows unreviewed workflow code to execute on self-hosted runners; fork secrets remain withheld and the run token remains read-only.

Affected products

Gitea Open Source Git Server: through 1.27.2

References

https://blog.gitea.com/release-of-1.27.3/
https://github.com/go-gitea/gitea/pull/39005
https://github.com/go-gitea/gitea/pull/39018
https://github.com/go-gitea/gitea/releases/tag/v1.27.3
https://github.com/go-gitea/gitea/security/advisories/GHSA-v2w8-m4gr-qj65

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