Vulnerability · Published Jul 9, 2026 · Assigned by GitHub_M
CVE-2026-59220Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
Medium 6.5
In plain English
A medium-severity regular-expression denial of service in open-webui from open-webui. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | open-webui | 0.10.0 | GHSA-ffpj-xv5c-p3gw |
| PyPI | open-webui | 0.10.0 | PYSEC-2026-3596 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| open-webui | open-webui | >= 0.9.2, < 0.10.0 |
Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H