CVE-2026-103620 Missing authorization in GitHub Enterprise Server allowed repository writers to replace default branches via GraphQL
Repository writers can bypass pull-request review requirements by replacing the default branch via GraphQL, affecting GitHub Enterprise Server.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-103620?
CVE-2026-103620 is a medium-severity missing authorization vulnerability in Github Enterprise Server, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-862
Which versions are affected by CVE-2026-103620?
It affects 1 product.
Products include Github Enterprise Server.
How do I fix CVE-2026-103620?
No fix has been published for CVE-2026-103620 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-103620 being exploited?
There is no known exploitation of CVE-2026-103620 in the wild and no public exploit code.
Other vulnerabilities in Github Enterprise Server
- CVE-2024-4985 Auth bypass in Enterprise Server
- CVE-2022-23739 Missing authorization in GitHub Enterprise Server
- CVE-2022-46255 Improper Limitation of a Pathname to a Restricted Directory in GitHub Enterprise Server leading to RCE
- CVE-2021-22869 Improper access control in GitHub Enterprise Server allows self-hosted runners to execute outside their control group
- CVE-2024-9487 Auth bypass in Enterprise Server
Sources
Also known as GHSA-mj9w-xm4p-h2mp.