Description
An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting an authorization bypass in the enable_auto_merge mutation for pull requests. This issue only affected repositories that allow forking as the attack relies on opening a pull request from an attacker-controlled fork into the target repository. Exploitation was only possible in specific scenarios. It required a clean pull request status and only applied to branches without branch protection rules enabled. This vulnerability affected GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11, and was fixed in versions 3.19.2, 3.18.5, and 3.17.11. This vulnerability was reported via the GitHub Bug Bounty program.
Published: 2026-02-18
Score: 7.1 High
EPSS: < 1% Very Low
KEV: No
Impact: Unauthorized Code Integration
Action: Apply Patch
AI Analysis

Impact

An incorrect authorization flaw in GitHub Enterprise Server allows an attacker to merge a pull request from an attacker-controlled fork into a target repository without having push rights. The vulnerability is triggered via the enable_auto_merge mutation for pull requests and is limited to situations where the repository allows forking, the pull request is clean, and there are no branch protection rules in place. This bypass permits the insertion of arbitrary code or configuration changes into the repository, potentially compromising the integrity of the codebase and downstream deployments. The weakness reflects an authorization bypass (CWE‑863).

Affected Systems

GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11 are affected. Updates to 3.19.2, 3.18.5, and 3.17.11 contain the fix.

Risk and Exploitability

The vulnerability carries a CVSS base score of 7.1, indicating high severity. The EPSS score is less than 1%, showing a low probability of exploitation, and it is not listed in the CISA KEV catalog. Exploitability requires a forking‑capable user, a clean pull request, and the absence of protected branches, which limits the attack surface but still allows a determined adversary to inject code into repositories that accept forks.

Generated by OpenCVE AI on April 15, 2026 at 15:46 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade GitHub Enterprise Server to version 3.19.2 or later, 3.18.5 or later, or 3.17.11 or later.
  • Disable repository forking for critical repositories until the patch is applied to reduce the attack surface.
  • Enable or enforce branch protection rules and disable auto-merge for forks to prevent unauthorized merges.

Generated by OpenCVE AI on April 15, 2026 at 15:46 UTC.

Tracking

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Advisories

No advisories yet.

History

Wed, 08 Apr 2026 22:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-918
References

Wed, 08 Apr 2026 22:15:00 +0000

Type Values Removed Values Added
Description A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an authenticated user to access internal services bound to loopback or unspecified addresses, potentially disrupting background job processing, accessing administrative endpoints, metrics, and profiling data, or manipulating job queues. Exploitation required an authenticated user with permissions to configure webhooks (repository, organization, or GitHub App administrator privileges). This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.14.22, 3.15.17, 3.16.13, 3.17.10, 3.18.4, and 3.19.1. This vulnerability was reported via the GitHub Bug Bounty program. An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting an authorization bypass in the enable_auto_merge mutation for pull requests. This issue only affected repositories that allow forking as the attack relies on opening a pull request from an attacker-controlled fork into the target repository. Exploitation was only possible in specific scenarios. It required a clean pull request status and only applied to branches without branch protection rules enabled. This vulnerability affected GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11, and was fixed in versions 3.19.2, 3.18.5, and 3.17.11. This vulnerability was reported via the GitHub Bug Bounty program.
Title Server-Side Request Forgery in GitHub Enterprise Server Webhook Delivery Allows Access to Internal Services Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests
Weaknesses CWE-863
References
Metrics cvssV4_0

{'score': 7.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:L/SA:L'}

 cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:L/SI:H/SA:N'}

Tue, 03 Mar 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-863
References

Tue, 03 Mar 2026 16:00:00 +0000

Type Values Removed Values Added
Description An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting an authorization bypass in the enable_auto_merge mutation for pull requests. This issue only affected repositories that allow forking as the attack relies on opening a pull request from an attacker-controlled fork into the target repository. Exploitation was only possible in specific scenarios. It required a clean pull request status and only applied to branches without branch protection rules enabled. This vulnerability affected GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11, and was fixed in versions 3.19.2, 3.18.5, and 3.17.11. This vulnerability was reported via the GitHub Bug Bounty program. A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an authenticated user to access internal services bound to loopback or unspecified addresses, potentially disrupting background job processing, accessing administrative endpoints, metrics, and profiling data, or manipulating job queues. Exploitation required an authenticated user with permissions to configure webhooks (repository, organization, or GitHub App administrator privileges). This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.14.22, 3.15.17, 3.16.13, 3.17.10, 3.18.4, and 3.19.1. This vulnerability was reported via the GitHub Bug Bounty program.
Title Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests Server-Side Request Forgery in GitHub Enterprise Server Webhook Delivery Allows Access to Internal Services
Weaknesses CWE-918
References
Metrics cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:L/SI:H/SA:N'}

 cvssV4_0

{'score': 7.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:L/SA:L'}

Thu, 19 Feb 2026 22:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'}

Thu, 19 Feb 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 19 Feb 2026 10:30:00 +0000

Type Values Removed Values Added
First Time appeared Github
Github enterprise Server
Vendors & Products Github
Github enterprise Server

Wed, 18 Feb 2026 21:00:00 +0000

Type Values Removed Values Added
Description An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting an authorization bypass in the enable_auto_merge mutation for pull requests. This issue only affected repositories that allow forking as the attack relies on opening a pull request from an attacker-controlled fork into the target repository. Exploitation was only possible in specific scenarios. It required a clean pull request status and only applied to branches without branch protection rules enabled. This vulnerability affected GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11, and was fixed in versions 3.19.2, 3.18.5, and 3.17.11. This vulnerability was reported via the GitHub Bug Bounty program.
Title Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests
Weaknesses CWE-863
References
Metrics cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:L/SI:H/SA:N'}

Subscriptions

Github Enterprise Server
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_P

Published:

Updated: 2026-04-14T15:09:57.585Z

Reserved: 2026-02-05T17:14:39.098Z

Link: CVE-2026-1999

cve-icon Vulnrichment

Updated: 2026-02-19T14:32:06.660Z

cve-icon NVD

Status : Modified

Published: 2026-02-18T21:16:24.147

Modified: 2026-04-08T22:16:20.910

Link: CVE-2026-1999

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T17:15:10Z

Weaknesses