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Enterprise ServerApplication · GitHub

CVE-2026-9132

MEDIUM · 6.5 CVSS v3.1 Published 2026-06-30
Fix available
A fix is available. Upgrade to 3.17.17 / 3.18.11 or later.
See remediation →
71/100
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
A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed an authenticated user to read source code from private repositories they did not have access to. The Copilot pull request description diff summary endpoint accepted a cross-repository comparison range and rendered the resulting diff without verifying that the requesting user was authorized to view the target repository. Exploitation required an authenticated account on the instance with read access to at least one repository to use as the comparison base. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.17.17, 3.18.11, 3.19.8, and 3.20.4. 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

Missing authorization vulnerability in GitHub Enterprise Server's Copilot pull request description diff summary endpoint allowed authenticated users to read source code from private repositories by supplying a cross-repository comparison range without the endpoint verifying user authorization to access the target repository.

MitigationUpgrade GitHub Enterprise Server to version 3.17.17, 3.18.11, 3.19.8, 3.20.4, or later to apply the patched authorization check.

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:< 3.17.17>= 3.18.0, < 3.18.11>= 3.19.0, < 3.19.8>= 3.20.0, < 3.20.4

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
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/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
    Access the Management Console or run `ghe-version` command via SSH to the appliance to determine the installed version
    Affected if The installed version falls within any of these ranges: < 3.17.17, >= 3.18.0 and < 3.18.11, >= 3.19.0 and < 3.19.8, or >= 3.20.0 and < 3.20.4
  2. Confirm Copilot is enabled
    Navigate to the Management Console under GitHub Copilot settings or query the Copilot configuration via API to verify if Copilot is active for the instance
    Affected if Copilot is enabled and the server version is in the affected ranges listed above
  3. Review audit logs for cross-repository access patterns
    Search the GitHub Enterprise audit log for API calls to the Copilot pull request description diff summary endpoint (typically /copilot/pull_request/diff_summary) with cross-repository comparison parameters
    Affected if Audit logs show unaUTHORIZED cross-repository diff summary requests from users who lack access to the target repository

The environment is affected if GitHub Enterprise Server is running a version prior to 3.17.17, 3.18.11, 3.19.8, or 3.20.4 and has Copilot enabled, allowing potential unauthorized cross-repository code access through the diff summary endpoint.

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 3.17.17 / 3.18.11 / 3.19.8 or later
Fixed in 3.17.173.18.113.19.8
Interim mitigation

Upgrade GitHub Enterprise Server to version 3.17.17, 3.18.11, 3.19.8, 3.20.4, or later to apply the patched authorization check.

Recommended fix High confidence

Upgrade to version 3.20.4 or later (such as 3.21+)

  1. 1. Identify the current GitHub Enterprise Server version by navigating to the site admin dashboard or using the gh CLI with admin privileges
  2. 2. Based on the current version, determine the appropriate upgrade path to reach a fixed release (3.17.17, 3.18.11, 3.19.8, or 3.20.4 or later)
  3. 3. Review the GitHub Enterprise Server upgrade prerequisites and ensure sufficient backup of the instance
  4. 4. Perform the upgrade following GitHub's official upgrade documentation for Enterprise Server
  5. 5. After upgrade, verify the Copilot pull request description diff summary endpoint now properly enforces authorization checks
  6. 6. Confirm that users can no longer access source code from repositories they are not authorized to view
Caveat Standard GitHub Enterprise Server upgrade considerations apply - review release notes for migration requirements and test 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
  • 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-2026-9132 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data