CVE-2026-59220

Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config

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

open-webui

CVSS v3.1 GITHUB

6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS

0.57% chance of exploitation in the next 30 days, 46th percentile

Published

2026-07-09

Proof-of-concept exploits (1)

• advisories/GHSA-ffpj-xv5c-p3gw

Security advisories

• open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw
• open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331

References

• CVE Record
• NVD entry