A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed a repository contributor to cause the appliance to issue requests to attacker-controlled internal hosts, which could be chained to achieve remote code execution on the appliance. The secret scanning validator for GCP service account credentials trusted the token endpoint embedded in a committed credential and issued a request to it without restricting the destination. Exploitation required an authenticated user with permission to push to a repository on an instance with GitHub Advanced Security and secret scanning validity checks enabled, a non-default configuration. This vulnerability affected GitHub Enterprise Server 3.20, 3.21, and 3.22 and was fixed in versions 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported through the GitHub Bug Bounty program.