An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.0 before 15.10.8, all versions starting from 15.11 before 15.11.7, all versions starting from 16.0 before 16.0.2. A Regular Expression Denial of Service was possible via sending crafted payloads to the preview_markdown endpoint.
The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Gitlab | Gitlab | 12.0.0 (including) | 15.10.8 (excluding) |
| Gitlab | Gitlab | 15.11.0 (including) | 15.11.7 (excluding) |
| Gitlab | Gitlab | 16.0.0 (including) | 16.0.2 (excluding) |
| Gitlab | Ubuntu | bionic | * |
| Gitlab | Ubuntu | esm-apps/xenial | * |
| Gitlab | Ubuntu | trusty | * |
| Gitlab | Ubuntu | xenial | * |
Attackers can create crafted inputs that
intentionally cause the regular expression to use
excessive backtracking in a way that causes the CPU
consumption to spike.