A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed a repository collaborator with write access to delete the current default branch through the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories that required pull-request review but did not restrict branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content. This vulnerability affected supported GitHub Enterprise Server releases in the 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.18.16, 3.19.13, 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported via the GitHub Bug Bounty program.
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History
Tue, 20 Oct 2026 19:45:00 +0000
| Type | Values Removed | Values Added |
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| CPEs | cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* | |
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cvssV3_1
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Thu, 08 Oct 2026 07:30:00 +0000
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ssvc
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Wed, 07 Oct 2026 03:00:00 +0000
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Github
Github enterprise Server |
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| Vendors & Products |
Github
Github enterprise Server |
Tue, 06 Oct 2026 19:00:00 +0000
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| Description | A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed a repository collaborator with write access to delete the current default branch through the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories that required pull-request review but did not restrict branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content. This vulnerability affected supported GitHub Enterprise Server releases in the 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.18.16, 3.19.13, 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported via the GitHub Bug Bounty program. | |
| Title | Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL | |
| Weaknesses | CWE-862 | |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_P
Published: 2026-10-06T18:56:41.101Z
Updated: 2026-10-07T16:32:08.448Z
Reserved: 2026-09-30T23:02:34.862Z
Link: CVE-2026-103620
Updated: 2026-10-07T16:31:59.589Z
Status : Analyzed
Published: 2026-10-06T19:17:39.700
Modified: 2026-10-20T19:33:53.047
Link: CVE-2026-103620
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