Vulnerability Description
An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting an authorization bypass in the enable_auto_merge mutation for pull requests. This issue only affected repositories that allow forking as the attack relies on opening a pull request from an attacker-controlled fork into the target repository. Exploitation was only possible in specific scenarios. It required a clean pull request status and only applied to branches without branch protection rules enabled. This vulnerability affected GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11, and was fixed in versions 3.19.2, 3.18.5, and 3.17.11. This vulnerability was reported via the GitHub Bug Bounty program.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Github | Enterprise Server | < 3.17.11 |
Related Weaknesses (CWE)
References
- https://docs.github.com/en/[email protected]/admin/release-notes#3.17.11
- https://docs.github.com/en/[email protected]/admin/release-notes#3.18.5
- https://docs.github.com/en/[email protected]/admin/release-notes#3.19.2
FAQ
What is CVE-2026-1999?
CVE-2026-1999 is a vulnerability with a CVSS score of 6.5 (MEDIUM). An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting ...
How severe is CVE-2026-1999?
CVE-2026-1999 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-1999?
Check the references section above for vendor advisories and patch information. Affected products include: Github Enterprise Server.