CVE-2026-6736
Summary
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.
Impact & exploitability
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Affected products we track (1)
Recommendation
Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.
Additional information
- NVD record
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18Advisory
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15Advisory
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9Advisory
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6Advisory
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2Advisory