GitHub Enterprise Server <3.19.2 Enable Auto Merge Auth Bypass
CVE-2026-1999 Published on February 18, 2026
Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests
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.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-1999 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-1999
Want to know whenever a new CVE is published for github Enterprise Server? stack.watch will email you.
Affected Versions
GitHub Enterprise Server:- Version 3.17.0 and below 3.17.11 is affected.
- Version 3.18.0 and below 3.18.5 is affected.
- Version 3.19.0 and below 3.19.2 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.