An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.10 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. A regular expression used for handling user input (notes, comments, etc) was susceptible to catastrophic backtracking that could cause a DOS attack.
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 | 12.10.0 (including) | 14.3.6 (excluding) |
| Gitlab | Gitlab | 14.4.0 (including) | 14.4.4 (excluding) |
| Gitlab | Gitlab | 14.5.0 (including) | 14.5.2 (excluding) |
| 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.
Potential Mitigations
Related Attack Patterns
References
- https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39933.json
- https://gitlab.com/gitlab-org/gitlab/-/issues/340449
- https://hackerone.com/reports/1320077
- https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39933.json
- https://gitlab.com/gitlab-org/gitlab/-/issues/340449
- https://hackerone.com/reports/1320077