CVE-2026-5845: CWE-639 Authorization bypass through User-Controlled key in GitHub Enterprise Server
CVE-2026-5845 is an authorization bypass vulnerability in GitHub Enterprise Server affecting versions prior to 3. 21. It allows an authenticated attacker to access private repositories outside their intended scope, including write operations, by exploiting an authorization fallback that treats revoked or deleted installations as global contexts. This flaw can be chained with token revocation timing and SSH push attribution to reuse victim-scoped tokens. The vulnerability was fixed in multiple patched versions starting from 3. 14. 26 through 3. 20. 1. It was reported through the GitHub Bug Bounty program and has a high severity rating.
AI Analysis
Technical Summary
This vulnerability arises from improper authorization in the scoped user-to-server (ghu_) token mechanism in GitHub Enterprise Server. When an installation is revoked or deleted, the authorization fallback incorrectly treats it as a global installation context, enabling an attacker with authenticated access to bypass intended repository access restrictions. This can lead to unauthorized read and write access to private repositories outside the attacker's installation scope. The issue affects all GitHub Enterprise Server versions before 3.21 and was addressed in patched releases 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26.
Potential Impact
An authenticated attacker with a scoped token could exploit this vulnerability to access private repositories beyond their authorized installation scope, including performing write operations. This could lead to unauthorized code changes or data exposure within private repositories. The vulnerability does not affect GitHub Enterprise Server versions 3.21 and later, where the issue has been fixed.
Mitigation Recommendations
Fixed versions of GitHub Enterprise Server are available starting from 3.14.26 up to 3.20.1 and later. Users should upgrade to version 3.21 or any of these patched releases to remediate this vulnerability. Since this is an on-premises product, administrators must apply the appropriate update. There is no indication that the vulnerability is mitigated by configuration changes alone. Patch status is confirmed by the vendor advisory embedded in the description.
CVE-2026-5845: CWE-639 Authorization bypass through User-Controlled key in GitHub Enterprise Server
Description
CVE-2026-5845 is an authorization bypass vulnerability in GitHub Enterprise Server affecting versions prior to 3. 21. It allows an authenticated attacker to access private repositories outside their intended scope, including write operations, by exploiting an authorization fallback that treats revoked or deleted installations as global contexts. This flaw can be chained with token revocation timing and SSH push attribution to reuse victim-scoped tokens. The vulnerability was fixed in multiple patched versions starting from 3. 14. 26 through 3. 20. 1. It was reported through the GitHub Bug Bounty program and has a high severity rating.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability arises from improper authorization in the scoped user-to-server (ghu_) token mechanism in GitHub Enterprise Server. When an installation is revoked or deleted, the authorization fallback incorrectly treats it as a global installation context, enabling an attacker with authenticated access to bypass intended repository access restrictions. This can lead to unauthorized read and write access to private repositories outside the attacker's installation scope. The issue affects all GitHub Enterprise Server versions before 3.21 and was addressed in patched releases 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26.
Potential Impact
An authenticated attacker with a scoped token could exploit this vulnerability to access private repositories beyond their authorized installation scope, including performing write operations. This could lead to unauthorized code changes or data exposure within private repositories. The vulnerability does not affect GitHub Enterprise Server versions 3.21 and later, where the issue has been fixed.
Mitigation Recommendations
Fixed versions of GitHub Enterprise Server are available starting from 3.14.26 up to 3.20.1 and later. Users should upgrade to version 3.21 or any of these patched releases to remediate this vulnerability. Since this is an on-premises product, administrators must apply the appropriate update. There is no indication that the vulnerability is mitigated by configuration changes alone. Patch status is confirmed by the vendor advisory embedded in the description.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_P
- Date Reserved
- 2026-04-08T18:28:58.486Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69e85dc119fe3cd2cd7080a1
Added to database: 4/22/2026, 5:33:53 AM
Last enriched: 4/22/2026, 5:35:04 AM
Last updated: 4/22/2026, 9:16:41 AM
Views: 14
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