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.
History

Fri, 08 May 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 07 May 2026 23:15:00 +0000

Type Values Removed Values Added
First Time appeared Github
Github enterprise Server
Vendors & Products Github
Github enterprise Server

Thu, 07 May 2026 21:45:00 +0000

Type Values Removed Values Added
Title Missing Authentication for Critical Function vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to create a local user account bypassing the external identity provider Authentication bypass vulnerability in GitHub Enterprise Server allowed creation of local user accounts bypassing the configured external identity provider

Thu, 07 May 2026 21:30:00 +0000

Type Values Removed Values Added
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.
Title Missing Authentication for Critical Function vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to create a local user account bypassing the external identity provider
Weaknesses CWE-306
References
Metrics cvssV4_0

{'score': 6.3, '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_P

Published: 2026-05-07T21:14:33.490Z

Updated: 2026-05-08T13:57:18.111Z

Reserved: 2026-04-21T02:53:28.704Z

Link: CVE-2026-6736

cve-icon Vulnrichment

Updated: 2026-05-08T13:57:14.886Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-07T22:16:36.753

Modified: 2026-05-08T15:49:00.693

Link: CVE-2026-6736

cve-icon Redhat

No data.