VulnerabilityAnalyzed

CVE-2026-6736

MEDIUM 6.3EPSS 0.27%

Does this matter?

Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.

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 4.0: 6.3 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.27% probability · 19th percentile
CISA KEV: Not listed
Weakness: CWE-306
Affected: github/enterprise server
Source: product-cna@github.com

References

https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2Release Notes, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.