CVE-2026-6736 json
Authentication bypass vulnerability in GitHub Enterprise Server allowed creation of local user accounts bypassing the configured external identity provider
published 2026-05-07 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-28461
- cvss
- 6.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 18%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- GitHub Enterprise Server 3.16.18, 3.17.15, 3.18.9, 3.19.6, 3.20.2
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 6 mo ago
Exploit prediction
0.27% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.3 | 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 |
| CNA | 4.0 | 6.3 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
Affected products
- GitHub Enterprise Server
Classification
- Weakness
-
- CWE-306 Missing Authentication for Critical Functionality
References
-
docs.github.com
/en/enterprise-server@3.16/admin/release-notes#3.16.18
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.17/admin/release-notes#3.17.15
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.18/admin/release-notes#3.18.9
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.19/admin/release-notes#3.19.6
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.20/admin/release-notes#3.20.2
release-notes, vendor-advisory
Sources
- CVE List CVE-2026-6736
- NVD CVE-2026-6736
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.