GitLab has remediated an issue in GitLab CE/EE affecting all versions from 19.2 before 19.2.8, 19.3 before 19.3.5, and 19.4 before 19.4.2 that, under certain conditions, could have allowed an unauthenticated user to execute arbitrary code on the GitLab server via a specially crafted regular expression in a CI/CD configuration, due to insufficient regular expression validation. Note: The vulnerable code resides in regcomp.c in Ruby’s bundled Onigmo regular expression engine, rather than GitLab’s own application source. GitLab ships Ruby with its packages and applies a patch to that bundled runtime. The upstream fix is Ruby pull request #19020 (commits 7cfe8dc8 and cf35145f), first released in Ruby 4.0.8.