GitLab Mirror Sync URL Validation flaw (8.318.11.5 & 19.x before patch)
CVE-2026-12635 Published on June 25, 2026
Reliance on Reverse DNS Resolution for a Security-Critical Action in GitLab
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.
Vulnerability Analysis
CVE-2026-12635 can be exploited with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Reliance on Reverse DNS Resolution for a Security-Critical Action
The software 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.
Products Associated with CVE-2026-12635
Want to know whenever a new CVE is published for GitLab? stack.watch will email you.
Affected Versions
GitLab:- Version 8.3 and below 18.11.6 is affected.
- Version 19.0 and below 19.0.3 is affected.
- Version 19.1 and below 19.1.1 is affected.