An unauthenticated user can trigger a denial of service on GitLab by sending a specially crafted JSON payload that bypasses input validation. The flaw stems from improper handling of the specified quantity field in the payload, allowing the server to crash or exhaust resources. The vulnerability is classified under CWE-1284 and could lead to loss of availability for the affected instance.

All GitLab Community Edition and Enterprise Edition installations from version 12.10 up to, but not including, 18.8.9, 18.9 up to, but not including, 18.9.5, and 18.10 up to, but not including, 18.10.3 are impacted. Newer releases (18.8.9, 18.9.5, 18.10.3 and above) have the fix applied.

The CVSS score of 7.5 indicates a high severity. The metadata does not contain an EPSS value, so the precise exploitation probability is unknown, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector, inferred from the description, is that an attacker can supply arbitrary JSON data over an unauthenticated HTTP request to the vulnerable endpoint. No special privileges are required, and the impact is limited to denial of service rather than data compromise. Organizations running vulnerable GitLab instances should consider patching promptly.