An issue has been discovered in GitLab CE/EE affecting all versions starting from 10.3 before 15.11.10, all versions starting from 16.0 before 16.0.6, all versions starting from 16.1 before 16.1.1. A Regular Expression Denial of Service was possible via sending crafted payloads to the preview_markdown endpoint.
Weakness
The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Gitlab | Gitlab | 10.3.0 (including) | 15.11.10 (excluding) |
| Gitlab | Gitlab | 16.0.0 (including) | 16.0.6 (excluding) |
| Gitlab | Gitlab | 16.1.0 (including) | 16.1.1 (excluding) |
| Gitlab | Ubuntu | bionic | * |
| Gitlab | Ubuntu | esm-apps/xenial | * |
| Gitlab | Ubuntu | trusty | * |
| Gitlab | Ubuntu | xenial | * |
Extended Description
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.