CVE-2026-1999 HIGH

CVE-2026-1999: Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests

Vendor Github
Product Enterprise Server
Weakness CWE-863 · Incorrect authorization
Published February 18, 2026
Last update April 14, 2026

CVSS base score

7.1/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:L/SI:H/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

February 18, 2026 CVE published
April 14, 2026 Record updated