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Enterprise ServerApplication · GitHub

CVE-2026-14340

MEDIUM · 5.0 CVSS v3.1 Published 2026-07-01
Fix available
A fix is available. Upgrade to 3.16.20 / 3.17.17 or later.
See remediation →
56/100
Remediation priority · Elevated
Remotely reachable Zero-click 7 weeks old

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 incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed a user-to-server token scoped to a GitHub App installation to perform certain write operations on public repositories outside the token's intended scope. This was possible because the authorization check only verified that the installation had read permissions on the target repository rather than verifying that the token's installation was explicitly granted access to that repository. An attacker who obtained a victim's user-to-server token could create issues, issue comments, commit comments, and private vulnerability reports on any public repository, appearing as the victim user with no indication of the app involvement. This vulnerability was fixed by adding a repository scope check for user-to-server tokens issued by global apps. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.21.2, 3.20.4, 3.19.8, 3.18.11, 3.17.17, 3.16.20. This vulnerability was reported via the GitHub Bug Bounty program.

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

GitHub Enterprise Server had an incorrect authorization check for user-to-server tokens tied to GitHub App installations. The system only verified that the installation had read permissions on the target repository, rather than checking whether the token's installation was explicitly granted write access to that repository. This allowed attackers with a stolen user-to-server token to create issues, comments, and vulnerability reports on any public repository, appearing as the victim user.

MitigationUpgrade GitHub Enterprise Server to a fixed version (3.21.2, 3.20.4, 3.19.8, 3.18.11, 3.17.17, or 3.16.20 or later). Revoke any user-to-server tokens that may have been exposed, as the fix adds proper repository scope validation for global app tokens.

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:< 3.16.20>= 3.17.0, < 3.17.17>= 3.18.0, < 3.18.11>= 3.19.0, < 3.19.8>= 3.20.0, < 3.20.4>= 3.21.0, < 3.21.2

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
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/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 your GitHub Enterprise Server version
    Run 'ghe-version' from the administrative SSH console or check the GitHub Enterprise Management Console dashboard under 'Site administration' > 'About'
    Affected if The installed version matches one of the affected ranges: < 3.16.20, >= 3.17.0 and < 3.17.17, >= 3.18.0 and < 3.18.11, >= 3.19.0 and < 3.19.8, >= 3.20.0 and < 3.20.4, or >= 3.21.0 and < 3.21.2
  2. Determine if GitHub Apps with user-to-server tokens are in use
    Navigate to 'Site admin' > 'GitHub Apps' in the management console and review installed GitHub Apps. Check each app's settings for whether 'User-to-server token' authorization option is enabled
    Affected if GitHub Apps are installed and configured to issue user-to-server tokens to users
  3. Identify public repositories in your environment
    Use the GitHub Enterprise admin API or navigate to 'Site admin' > 'Repositories' and filter for repositories where visibility is set to 'Public'
    Affected if Any public repositories exist in the GitHub Enterprise Server instance
  4. Review audit logs for suspicious GitHub App token activity
    Query the enterprise audit log for events involving 'github_app_user_to_server' action types, filtering for unexpected issue creation, comment, or vulnerability report events on public repositories. Use 'ghe-audit-log-tail' or the web UI under 'Site admin' > 'Audit log'
    Affected if Audit logs show GitHub App user-to-server tokens performing write actions (issues, comments, vulnerability alerts) on public repositories that the token owner did not explicitly authorize

You are affected if your GitHub Enterprise Server version is within any of the affected ranges AND you have GitHub Apps configured with user-to-server tokens AND public repositories exist in your environment.

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 3.16.20 / 3.17.17 / 3.18.11 or later
Fixed in 3.16.203.17.173.18.11
Interim mitigation

Upgrade GitHub Enterprise Server to a fixed version (3.21.2, 3.20.4, 3.19.8, 3.18.11, 3.17.17, or 3.16.20 or later). Revoke any user-to-server tokens that may have been exposed, as the fix adds proper repository scope validation for global app tokens.

Recommended fix High confidence

Upgrade to GitHub Enterprise Server 3.21.2 (or latest 3.22.x if available)

  1. 1. Back up your GitHub Enterprise Server data, including database, configurations, and repositories.
  2. 2. Review the GitHub Enterprise Server upgrade documentation for your current version.
  3. 3. Download the appropriate fixed version (3.21.2, 3.20.4, 3.19.8, 3.18.11, 3.17.17, or 3.16.20) from the GitHub Enterprise downloads page.
  4. 4. Ensure your system meets the hardware and software requirements for the target version.
  5. 5. Run the upgrade procedure using the administrative console or command-line tools provided by GitHub.
  6. 6. After upgrade, verify that the user-to-server tokens for GitHub Apps now correctly enforce repository scope restrictions.
  7. 7. Test that tokens scoped to specific repositories cannot perform write operations on other public repositories.
  8. 8. Monitor system logs and user feedback for any authorization-related anomalies.
Caveat Review release notes for breaking changes between your current version and target version; test thoroughly in staging before production deployment

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

Fix this in Enterprise Server Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

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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-2026-14340 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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