CVE-2026-5845

Improper authorization fallback allows scoped user-to-server token installation escape in GitHub Enterprise Server

Published Apr 21, 2026 CVSS 4.0 · 7.2 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*
cpe:2.3:a:github:enterprise_server:3.20.0:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 9.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Github
Github enterprise Server
Vendors & Products Github
Github enterprise Server
Type Values Removed Values Added
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.
Title Improper authorization fallback allows scoped user-to-server token installation escape in GitHub Enterprise Server
Weaknesses CWE-639
References
Metrics cvssV4_0

{'score': 7.2, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_P
Published
Updated
Apr 22, 2026, 6:04 PM
Reserved
Apr 8, 2026, 6:28 PM
Status
Analyzed
Published
Apr 21, 2026, 11:16 PM
Modified
Oct 26, 2026, 9:10 PM