CVE-2026-5845

Critical

Description

An improper authorization vulnerability in scoped user-to-server (ghu_) token authorization in GitHub Enterprise Server allows an authenticated attacker to access private repositories outside the intended installation scope, which can include write operations, via an authorization fallback that treated a revoked/deleted installation as a global installation context, which could be chained with token revocation timing and SSH push attribution to obtain and reuse a victim-scoped token. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.

SeverityCritical
CVSS9.6
Exploit probability—
ProductGithub Enterprise Server
PublishedApr 21, 2026
First seenApr 21, 2026

How to fix

Update
  • github enterprise_server3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5 or later

Affected products

ProductAffected versionsFixed in
github enterprise_serverv < 3.14.26, 3.15.0 ≤ v < 3.15.21, 3.16.0 ≤ v < 3.16.17, 3.17.0 ≤ v < 3.17.14, 3.18.0 ≤ v < 3.18.8, 3.19.0 ≤ v < 3.19.5, 3.20.03.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5

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