ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-1999

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 a

Published Feb 18, 2026 · catalog updated Apr 14, 2026 · GitHub Enterprise Server

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-1999. EPSS is 0.36%. Act only if a listed version of GitHub Enterprise Server is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.36%
Remediation
Version ranges on file
Affected products
vendor GitHub Enterprise Server 3.18.0 <3.18.5

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 ena

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor GitHub Enterprise Server 3.18.0 <3.18.53.18.0 <3.18.5

How to fix CVE-2026-1999

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-1999. EPSS is 0.36%. Act only if a listed version of GitHub Enterprise Server is installed.

Which versions are affected?

Compare what you have installed with GitHub Enterprise Server 3.18.0 <3.18.5 3.18.0 <3.18.5. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.36%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 18, 2026 · EUVD

    Detected

    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-co

  2. Apr 14, 2026 · EUVD

    Updated

    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-co

Sources

  • CVE.orgVulnerability recordCVE-2026-1999

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-1999

    30-day exploitation probability 0.36%

    first.org
  • EUVDVulnerability recordEUVD-2026-7963

    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. Thi

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 7, 2026
  • CVE.orgNov 7, 2026
  • EUVDNov 7, 2026