CVE-2026-103620
mediumpriority · track · 26OT risk · elevatedEPSS 0.005 · 43 %ileDEUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2.3–6.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (15)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3764Microsoft GitHub Enterprise: Mehrere SchwachstellenDeutsch2026-10-06csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Microsoft GitHub Enterprise ausnutzen, um Daten zu manipulieren, und um beliebigen Programmcode auszuführen.
sources
Which sources assert this record, and when.
references (5) nvd
External citations — patches, advisories, analysis.
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.16Release NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.13Release NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.9Release NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.7Release NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.22/admin/release-notes#3.22.2Release NotesVendor Advisory
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan