CVE-2026-5845

Summary

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.

Impact & exploitability

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected products we track (1)

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Additional information

• NVD record
• https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.26Advisory
• https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.21Advisory
• https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.17Advisory
• https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.14Advisory
• https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.8Advisory
• https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.5Advisory
• https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.1Advisory