A Server-Side Request Forgery vulnerability was identified in GitHub Enterprise Server that allowed an attacker with the Site Administrator role to gain arbitrary code execution capability on the GitHub Enterprise Server instance. Exploitation required authenticated access to GitHub Enterprise Server as a user with the Site Administrator role. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.13 and was fixed in versions 3.12.5, 3.11.11, 3.10.13, and 3.9.16. This vulnerability was reported via the GitHub Bug Bounty program.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.