# CVE-2026-1999: Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests

> CVE-2026-1999: Incorrect Authorization vulnerability was identified in GitHub Enterprise Server that allowed unauthorized merging of pull requests. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-1999
Last updated: 2026-06-17T10:16:51Z

- Published: 2026-02-18 20:44 UTC · Updated: 2026-06-17 10:16 UTC · Assigner: GitHub\_P
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- EPSS: 0.36%, 29th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-863

## 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.

## Affected vendors and products

- GitHub: Enterprise Server

## Tracked companies

- [GitHub](https://rewindex.com/company/github.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-1999)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-1999)
- [https://docs.github.com/en/enterprise-server@3.17/admin/release-notes\#3.17.11](https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.11)
- [https://docs.github.com/en/enterprise-server@3.18/admin/release-notes\#3.18.5](https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.5)
- [https://docs.github.com/en/enterprise-server@3.19/admin/release-notes\#3.19.2](https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.2)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-1999 · Markdown: https://rewindex.com/cve/CVE-2026-1999.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-1999 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:13:38.971Z