CVE-2026-6736

Vulnerability Description

An authentication bypass vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to create a local user account, bypassing the configured external identity provider. When external authentication was enabled, the signup endpoint did not properly enforce the authentication restriction, allowing account creation and session establishment without identity provider validation. The created account was limited to the default base permissions configured on the instance. Exploitation required network access to a GHES instance configured with an external authentication provider. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.2, 3.19.6, 3.18.9, 3.17.15, and 3.16.18.

CVSS Score

Affected Products

Related Weaknesses (CWE)

References

• https://docs.github.com/en/[email protected]/admin/release-notes#3.16.18Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.17.15Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.18.9Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.19.6Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.20.2Release NotesVendor Advisory