An issue has been discovered in GitLab CE/EE affecting all versions starting from 9.3 before 16.0.8, all versions starting from 16.1 before 16.1.3, all versions starting from 16.2 before 16.2.2. A Regular Expression Denial of Service was possible via sending crafted payloads which use ProjectReferenceFilter 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 | 9.3 (including) | 16.0.8 (excluding) |
| Gitlab | Gitlab | 16.1 (including) | 16.1.3 (excluding) |
| Gitlab | Gitlab | 16.2 (including) | 16.2.2 (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.