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CVE-2026-1999

Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.17.11, 3.18.5, 3.19.2
2 proofs of concept on GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • GitHub Enterprise Server

    From 3.17.0 · fixed in 3.17.11; From 3.18.0 · fixed in 3.18.5; From 3.19.0 · fixed in 3.19.2

References 5

docs.github.com

GitHub · jwde/automerge-test

GitHub · manoelprovider20-lgtm/merge-authz-test