CVE-2026-1456
Description
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.7 before 18.7.4, and 18.8 before 18.8.4 that could have allowed an unauthenticated user to cause denial of service through CPU exhaustion by submitting specially crafted markdown files that trigger exponential processing in markdown preview.
Summary dbcve.org
GitLab CE/EE versions 18.7 before 18.7.4 and 18.8 before 18.8.4 contain a denial-of-service vulnerability in the markdown preview feature. An unauthenticated attacker can submit specially crafted markdown files containing nested or recursive structures that trigger exponential processing time, leading to CPU exhaustion and service unavailability.
Mitigation
Upgrade GitLab to version 18.7.4, 18.8.4, or later. Until patched, consider disabling or rate-limiting unauthenticated markdown preview functionality at the proxy or application level.