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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 5
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.16
product-cna@github.com
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.13
product-cna@github.com
https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.9
product-cna@github.com
https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.7
product-cna@github.com
https://docs.github.com/en/enterprise-server@3.22/admin/release-notes#3.22.2
product-cna@github.com