# CVE-2026-103620: Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL

> CVE-2026-103620: Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-103620
Last updated: 2026-10-20T19:33:53Z

- Published: 2026-10-06 18:56 UTC · Updated: 2026-10-20 19:33 UTC · Assigner: GitHub\_P
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- EPSS: 0.50%, 43th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-862

## 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.

## Affected vendors and products

- GitHub: Enterprise Server

## Tracked companies

- [GitHub](https://rewindex.com/company/github.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-103620)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-103620)
- [https://docs.github.com/en/enterprise-server@3.18/admin/release-notes\#3.18.16](https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.16)
- [https://docs.github.com/en/enterprise-server@3.19/admin/release-notes\#3.19.13](https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.13)
- [https://docs.github.com/en/enterprise-server@3.20/admin/release-notes\#3.20.9](https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.9)
- [https://docs.github.com/en/enterprise-server@3.21/admin/release-notes\#3.21.7](https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.7)
- [https://docs.github.com/en/enterprise-server@3.22/admin/release-notes\#3.22.2](https://docs.github.com/en/enterprise-server@3.22/admin/release-notes#3.22.2)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-103620 · Markdown: https://rewindex.com/cve/CVE-2026-103620.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-103620 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:13:11.694Z