CVE-2026-59220: Openwebui Open Webui

Medium severity, CVSS 6.5. EPSS: 0.6% chance of exploitation in the next 30 days.

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 products

• Openwebui Open Webui: from 0.9.2, before 0.10.0 (fixed in 0.10.0)

Published 2026-07-09. Last modified 2026-07-10.