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CVE-2026-1999

HIGH CVSS 4.0: 7.1 EPSS 0.03%
Updated Feb 19, 2026
GitHub
Parameter Value
CVSS 7.1 (HIGH)
Affected Versions 3.18.0 — 3.19.2
Fixed In 3.17.11
Type CWE-863 (Incorrect Authorization)
Vendor GitHub
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
Low
Partial disruption

CVSS Vector v4.0

Vulnerable Products 3

Configuration From (including) Up to (excluding)
Github Enterprise_Server
cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*
3.17.11
Github Enterprise_Server
cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*
3.18.0 3.18.5
Github Enterprise_Server
cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*
3.19.0 3.19.2