Improper access control in GitHub Enterprise Server leading to privilege escalation of organization member

An improper access control vulnerability was identified in the GitHub Enterprise Server API that allowed an organization member to escalate permissions and gain access to unauthorized repositories within an organization. This vulnerability affected all versions of GitHub Enterprise Server prior to 2.21 and was fixed in 2.20.9, 2.19.15, and 2.18.20. This vulnerability was reported via the GitHub Bug Bounty program.