medium6.5
CVE-2026-59220
Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
Impact
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.2 before 0.10.0, the SKILL_MENTION_RE and strip_re regular expressions in backend/open_webui/utils/middleware.py parsed <$skillId|label> skill mentions with overlapping quantifiers, allowing an authenticated chat message containing <$ without a closing > to trigger quadratic backtracking and block the asyncio event loop. This issue is fixed in version 0.10.0.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | open-webui | >= 0.9.2, < 0.10.0 | 0.10.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Openwebui | Open Webui | from 0.9.2 before 0.10.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-ffpj-xv5c-p3gw
- https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw
- https://nvd.nist.gov/vuln/detail/CVE-2026-59220
- https://github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331
- https://github.com/open-webui/open-webui/releases/tag/v0.10.0