An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed a scoped user-to-server token to escalate to full admin/owner privileges. An attacker would require an account with admin access to install a malicious GitHub App. This vulnerability was fixed in versions 3.3.17, 3.4.12, 3.5.9, and 3.6.5. This vulnerability was reported via the GitHub Bug Bounty program.
https://docs.github.com/en/enterprise-server%403.6/admin/release-notes#3.6.5
https://docs.github.com/en/enterprise-server%403.5/admin/release-notes#3.5.9
https://docs.github.com/en/enterprise-server%403.4/admin/release-notes#3.4.12
https://docs.github.com/en/enterprise-server%403.3/admin/release-notes#3.3.17