Vulnerability · Published May 7, 2026 · Assigned by GitHub_P
CVE-2026-6736Authentication bypass vulnerability in GitHub Enterprise Server allowed creation of local user accounts bypassing the configured external identity provider
Medium 6.3
In plain English
A medium-severity missing authentication in Enterprise Server from GitHub. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 19% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| GitHub | Enterprise Server | 3.16.0 – through 3.16.173.17.0 – through 3.17.143.18.0 – through 3.18.83.19.0 – through 3.19.53.20.0 – through 3.20.1 |
Weakness: CWE-306 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18 release-notes
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15 release-notes
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9 release-notes
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6 release-notes
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2 release-notes