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

> Attackers can bypass fork workflow approval checks via concurrency cancellation, executing unreviewed code on self-hosted runners.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-v2w8-m4gr-qj65

## What is CVE-2026-66877?

CVE-2026-66877 is a high-severity vulnerability in Gitea, published on 14 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-66877?


## How do I fix CVE-2026-66877?

No fix has been published for CVE-2026-66877 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66877 being exploited?

There is no known exploitation of CVE-2026-66877 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66877 and fix it if it is affected.

What it is: CVE-2026-66877 is a high-severity vulnerability in Gitea, published on 14 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-66877 in the wild and no public exploit code.

Affected product: Gitea. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66877/ (Markdown: https://insights.sbomify.com/CVE-2026-66877/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66877
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66877
- OSV: https://osv.dev/vulnerability/CVE-2026-66877

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66877/
Summaries are generated and may contain mistakes; the official description above is the record.