GitLab Community Edition/Enterprise Edition up to 18.11.5/19.0.2/19.1.0 URL Validation dns rebinding

Summaryinfo

A vulnerability was found in GitLab Community Edition and Enterprise Edition up to 18.11.5/19.0.2/19.1.0. It has been classified as problematic. The affected element is an unknown function of the component URL Validation Handler. Performing a manipulation results in dns rebinding. This vulnerability is known as CVE-2026-12635. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, was found in GitLab Community Edition and Enterprise Edition up to 18.11.5/19.0.2/19.1.0. This affects an unknown code block of the component URL Validation Handler. The manipulation with an unknown input leads to a dns rebinding vulnerability. CWE is classifying the issue as CWE-350. The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname. This is going to have an impact on confidentiality. The summary by CVE is:

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 8.3 before 18.11.6, 19.0 before 19.0.3, and 19.1 before 19.1.1 that under certain conditions could have allowed an authenticated user with maintainer-role permissions to make requests to internal network resources through mirror synchronization due to improper URL validation.

The advisory is shared at gitlab.com. This vulnerability is uniquely identified as CVE-2026-12635 since 06/18/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1583.002 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 322745 (GitLab 8.3 < 18.11.6 / 19.0 < 19.0.3 / 19.1 < 19.1.1 (CVE-2026-12635)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 18.11.6, 19.0.3 or 19.1.1 eliminates this vulnerability. The upgrade is hosted for download at docs.gitlab.com.

The vulnerability is also documented in the vulnerability database at Tenable (322745). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Bug Tracking Software

Vendor

• GitLab

Name

• Community Edition
• Enterprise Edition

Version

• 18.11.0
• 18.11.1
• 18.11.2
• 18.11.3
• 18.11.4
• 18.11.5
• 19.0
• 19.0.0
• 19.0.1
• 19.0.2
• 19.1.0

License

• open-source

Website

• Vendor: https://gitlab.com/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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