An improper authentication vulnerability was identified in GitHub Enterprise Server that allowed a bypass of Private Mode by using a specially crafted API request. To exploit this vulnerability, an attacker would need network access to the Enterprise Server appliance configured in Private Mode. This vulnerability affected all versions of GitHub Enterprise Server since 3.9 and was fixed in version 3.9.7, 3.10.4, and 3.11.1. This vulnerability was reported via the GitHub Bug Bounty program.