Vulnerability in Open-Webui
CVE-2026-59220
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.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (45.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- Open-Webui — versions >= 0.9.2, < 0.10.0
- Openwebui Open Webui
Weakness classification (CWE)
References
- github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw (Exploit, Mitigation, Vendor Advisory)
- github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331 (Patch)
- github.com/open-webui/open-webui/releases/tag/v0.10.0 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-59220?
- CVE-2026-59220 is a medium-severity vulnerability in Open-Webui, classified under Inefficient Regular Expression Complexity. CVSS score: 6.5/10. Published 2026-07-09.
- How severe is CVE-2026-59220?
- Medium severity. CVSS v3 base score is 6.5 out of 10.