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Enterprise ServerApplication · GitHub

CVE-2026-6736

MEDIUM · 6.5 CVSS v3.1 Published 2026-05-07
Fix available
A fix is available. Upgrade to 3.16.18 / 3.17.15 or later.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Authentication bypass in GitHub Enterprise Server allowed unauthenticated attackers to create local user accounts by exploiting the signup endpoint when external authentication (SAML/SSO) was enabled. The endpoint failed to enforce IdP validation, permitting account creation and session establishment without identity provider authentication. Created accounts only received default base permissions.

MitigationUpgrade GitHub Enterprise Server to one of the fixed versions (3.20.2, 3.19.6, 3.18.9, 3.17.15, or 3.16.18) or later. Verify external authentication is properly enforcing IdP restrictions post-upgrade.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Enterprise ServerApplication
Affected:< 3.16.18>= 3.17.0, < 3.17.15>= 3.18.0, < 3.18.9>= 3.19.0, < 3.19.6>= 3.20.0, < 3.20.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify GitHub Enterprise Server version
    Run the command `ghe-version` in the management shell, or access the Admin Console > Management Console and check the version displayed on the dashboard
    Affected if The installed version falls within any of these ranges: < 3.16.18, >= 3.17.0 and < 3.17.15, >= 3.18.0 and < 3.18.9, >= 3.19.0 and < 3.19.6, or >= 3.20.0 and < 3.20.2
  2. Verify if external authentication is enabled
    Access Admin Console > Authentication > External authentication, or inspect the LDAP/SAML configuration files in /etc/github under the authentication settings
    Affected if SAML, OAuth, or LDAP external authentication is currently enabled and configured to delegate user authentication to an IdP
  3. Confirm user registration is not restricted
    Check Admin Console > Authentication settings for the option 'Restrict email domain for signup' or 'Disable local authentication' - ensure the signup endpoint is accessible to unauthenticated requests
    Affected if Local user registration is allowed or the settings allow unauthenticated access to the signup endpoint when external authentication is active
  4. Audit for unexpected local user accounts
    Run `ghe-api /users` or access Admin Console > User accounts to list all users; compare against known IdP-provisioned accounts
    Affected if Local user accounts exist that were not provisioned through the configured identity provider, especially accounts with creation timestamps matching the period of vulnerability exposure

You are affected if your GitHub Enterprise Server version is in the vulnerable ranges AND external authentication (SAML/SSO) is enabled while the signup endpoint remains accessible to unauthenticated users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.16.18 / 3.17.15 / 3.18.9 or later
Fixed in 3.16.183.17.153.18.9
Interim mitigation

Upgrade GitHub Enterprise Server to one of the fixed versions (3.20.2, 3.19.6, 3.18.9, 3.17.15, or 3.16.18) or later. Verify external authentication is properly enforcing IdP restrictions post-upgrade.

Recommended fix High confidence

3.16.18, 3.17.15, 3.18.9, 3.19.6, 3.20.2, or 3.21+ (depending on current branch)

  1. 1. Identify the current GitHub Enterprise Server version by navigating to the admin dashboard or running 'ghe-version' from the CLI
  2. 2. Determine which version branch you are on (3.16.x, 3.17.x, 3.18.x, 3.19.x, or 3.20.x)
  3. 3. For 3.16.x branch: upgrade to version 3.16.18 or later
  4. 4. For 3.17.x branch: upgrade to version 3.17.15 or later
  5. 5. For 3.18.x branch: upgrade to version 3.18.9 or later
  6. 6. For 3.19.x branch: upgrade to version 3.19.6 or later
  7. 7. For 3.20.x branch: upgrade to version 3.20.2 or later
  8. 8. Alternatively, upgrade to version 3.21 or later which includes the fix
Caveat Standard GitHub Enterprise Server upgrade considerations apply - review release notes for your version path for any migration requirements or known issues

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Enterprise Server Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-6736 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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