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CVE-2026-103620

Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.18.*, 3.19.*, 3.20.*, 3.21.*, 3.22.*
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed a repository collaborator with write access to delete the current default branch through the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories that required pull-request review but did not restrict branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content. This vulnerability affected supported GitHub Enterprise Server releases in the 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.18.16, 3.19.13, 3.20.9, 3.21.7, and 3.22.2. 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 3.18.0 · fixed in 3.18.*; From 3.19.0 · fixed in 3.19.*; From 3.20.0 · fixed in 3.20.*; From 3.21.0 · fixed in 3.21.*; From 3.22.0 · fixed in 3.22.*

References 5

docs.github.com