GitHub Enterprise Server up to 3.17.10/3.18.4/3.19.1 Pull Request enable_auto_merge authorization

Summaryinfo

A vulnerability labeled as problematic has been found in GitHub Enterprise Server up to 3.17.10/3.18.4/3.19.1. Impacted is the function enable_auto_merge of the component Pull Request Handler. The manipulation results in authorization. This vulnerability is reported as CVE-2026-1999. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, was found in GitHub Enterprise Server up to 3.17.10/3.18.4/3.19.1. Affected is the function enable_auto_merge of the component Pull Request Handler. The manipulation with an unknown input leads to a authorization vulnerability. CWE is classifying the issue as CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. This is going to have an impact on integrity, and availability. CVE summarizes:

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.

The weakness was disclosed by ahacker1. The advisory is shared for download at docs.github.com. This vulnerability is traded as CVE-2026-1999 since 02/05/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available.

Upgrading to version 3.17.11, 3.18.5 or 3.19.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0460). Once again VulDB remains the best source for vulnerability data.

Affected

• Microsoft GitHub Enterprise

Productinfo

Type

• Bug Tracking Software

Vendor

• GitHub

Name

• Enterprise Server

Version

• 3.17.0
• 3.17.1
• 3.17.2
• 3.17.3
• 3.17.4
• 3.17.5
• 3.17.6
• 3.17.7
• 3.17.8
• 3.17.9
• 3.17.10
• 3.18.0
• 3.18.1
• 3.18.2
• 3.18.3
• 3.18.4
• 3.19.0
• 3.19.1

License

• open-source

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CPE 2.2info

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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