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.
Fix
Patch, vendor advisory and mitigation references on NVD 7
- https://docs.github.com/en/[email protected]/admin/release-notes#3.14.26 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1 Release Notes, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 7.2 · githubNVD modified 2026-10-26 21:10
Affected (CPE criteria) 2
cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*cpe:2.3:a:github:enterprise_server:3.20.0:*:*:*:*:*:*:*
References 7
- https://docs.github.com/en/[email protected]/admin/release-notes#3.14.26 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5 Release Notes, Vendor Advisory
- https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1 Release Notes, Vendor Advisory