# CVE-2026-5845: Improper authorization fallback allows scoped user-to-server token installation escape in GitHub Enterprise Server

> Authenticated attackers can access and modify private repositories outside their token scope due to improper authorization fallback logic in GitHub Enterprise Server.

- **Severity:** High 7.2 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** GHSA-29qm-pmxx-2p86

## What is CVE-2026-5845?

CVE-2026-5845 is a high-severity missing authorization vulnerability in Github Enterprise Server, published on 21 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An improper authorization vulnerability in scoped user-to-server (ghu_) token authorization in GitHub Enterprise Server allows an authenticated attacker to access private repositories outside the intended installation scope, which can include write operations, via an authorization fallback that treated a revoked/deleted installation as a global installation context, which could be chained with token revocation timing and SSH push attribution to obtain and reuse a victim-scoped token. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-5845?

It affects 1 product.


Products: Github Enterprise Server.

## How do I fix CVE-2026-5845?

No fix has been published for CVE-2026-5845 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5845 being exploited?

There is no known exploitation of CVE-2026-5845 in the wild and no public exploit code.

## Other vulnerabilities in Github Enterprise Server

- [CVE-2024-4985](https://insights.sbomify.com/CVE-2024-4985/): Auth bypass in Enterprise Server (critical 10.0)
- [CVE-2022-23739](https://insights.sbomify.com/CVE-2022-23739/): Missing authorization in GitHub Enterprise Server (critical 9.8)
- [CVE-2022-46255](https://insights.sbomify.com/CVE-2022-46255/): Improper Limitation of a Pathname to a Restricted Directory in GitHub Enterprise Server leading to RCE (critical 9.8)
- [CVE-2021-22869](https://insights.sbomify.com/CVE-2021-22869/): Improper access control in GitHub Enterprise Server allows self-hosted runners to execute outside their control group (critical 9.8)
- [CVE-2024-9487](https://insights.sbomify.com/CVE-2024-9487/): Auth bypass in Enterprise Server (critical 9.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5845 and fix it if it is affected.

What it is: CVE-2026-5845 is a high-severity missing authorization vulnerability in Github Enterprise Server, published on 21 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5845 in the wild and no public exploit code.

Affected product: Github Enterprise Server. 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-2026-5845/ (Markdown: https://insights.sbomify.com/CVE-2026-5845/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5845
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5845
- OSV: https://osv.dev/vulnerability/CVE-2026-5845

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5845/
Summaries are generated and may contain mistakes; the official description above is the record.