CVE-2026-6736: github enterprise_server

Vulnerability summary

CVE-2026-6736 is a medium (CVSS 6.5) vulnerability in github enterprise_server. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34% of scored vulnerabilities.

Timeline

1. 07-05-2026
   PublishedVulnerability first disclosed.
2. 08-05-2026
   Last modifiedVulnerability information updated.

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.

• CWE-306Missing Authentication for Critical FunctionThe product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.