CVE-2026-59220 Details
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.
A denial-of-service vulnerability has been identified in Open WebUI versions 0.9.2 prior to 0.10.0. The issue arises from two regular expressions in the middleware utility that parse skill mention tags. These expressions can be exploited by sending an authenticated chat message containing an unclosed skill mention pattern, which triggers quadratic backtracking in the regex processing. This backtracking blocks the asyncio event loop, causing the application to freeze and become unresponsive to all users until the blocking worker is terminated.
Users can upgrade to Open WebUI version 0.10.0 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 9, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw | CISA-ADP | ExploitMitigationVendor Advisory |
| https://github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331 | [email protected] | Patch |
| https://github.com/open-webui/open-webui/releases/tag/v0.10.0 | [email protected] | ProductRelease Notes |
| https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw | [email protected] | ExploitMitigationVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1333 | Inefficient Regular Expression Complexity | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| openwebui open webui | >= 0.9.2, < 0.10.0 |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 10, 2026 | Initial Analysis | [email protected] |
| Jul 9, 2026 | CVE Modified | CISA-ADP |
| Jul 9, 2026 | New CVE Received | [email protected] |