GitLab has an authorization flaw that allows an authenticated user with project owner rights to bypass group fork prevention settings. The issue stems from improper authorization checks in the fork logic and is categorized as CWE‑863. Consequently, a project owner can create forks in groups that are intended to be protected, potentially exposing sensitive code or data.

GitLab Community Edition and Enterprise Edition are affected, including every release from version 11.2 up to but not including 18.9.6, all releases before 18.10.4 within the 18.10 lineage, and all releases before 18.11.1 within the 18.11 lineage. The vulnerability is present only in CE/EE builds with the default fork protection features enabled.

With a CVSS score of 2.7, the vulnerability is classified as low severity. No EPSS data is available and the bug is not listed in CISA's KEV catalog, indicating no known widespread exploitation. The attack requires an authenticated project owner to exploit the flaw, suggesting that it is not easily leveraged by unauthenticated attackers. As a result, the overall risk to organizations is low, but the potential impact on confidentiality where group fork prevention is critical should not be ignored.