CVE-2026-6736
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.
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 · 18th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-306
- Affected
- github/enterprise server
- Source
- product-cna@github.com
EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.