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Vulnerability record · CVE-2026-6736 · published 7 May 2026

CVE-2026-6736: Github enterprise server missing authentication for critical function vulnerability

Github · Enterprise Server

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.

6.3 CVSS 4.0 Medium EPSS 0.41% · top 67.1% CWE-306 · Missing authentication for critical function
6.3CVSS 4.0 base score
0.41%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References
17 Jun 2026Last modified by NVD

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/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://docs.github.com/en/[email protected]/admin/release-notes#3.16.18 Release NotesVendor Advisory
https://docs.github.com/en/[email protected]/admin/release-notes#3.17.15 Release NotesVendor Advisory
https://docs.github.com/en/[email protected]/admin/release-notes#3.18.9 Release NotesVendor Advisory
https://docs.github.com/en/[email protected]/admin/release-notes#3.19.6 Release NotesVendor Advisory
https://docs.github.com/en/[email protected]/admin/release-notes#3.20.2 Release NotesVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-6736), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.