Moderate severityNVD Advisory· Published Jul 9, 2026· Updated Jul 9, 2026
Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
CVE-2026-59220
Description
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
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
open-webuiPyPI | >= 0.9.2, < 0.10.0 | 0.10.0 |
Affected products
1- Range: <0.10.0, >=0.9.2
Patches
Vulnerability mechanics
References
5- github.com/advisories/GHSA-ffpj-xv5c-p3gwghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-59220ghsaADVISORY
- github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331ghsax_refsource_MISCWEB
- github.com/open-webui/open-webui/releases/tag/v0.10.0ghsax_refsource_MISCWEB
- github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gwghsax_refsource_CONFIRMWEB
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