What is CVE-2026-103620?
CVE-2026-103620 is a vulnerability classified as Missing Authorization, affecting Enterprise Server. This vulnerability is rated Medium, with a CVSS score of 6. Current sources do not report this vulnerability as exploited.
Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL
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Overview
Original source dataA 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.
Affected products and scope
The analysis could not be completed. The original vulnerability data remains available below.
Technical details
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Exploitability
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Technical impact
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Business impact
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Remediation
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Detection
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