Medium 6.5Published Jul 9, 2026

CVE-2026-59220Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config

Updated under an hour ago (Oct 27, 2026, 4:10 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 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.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-1333
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

open-webui open-webui open_webui:open_webui (from the name)	from 0.9.2, < 0.10.0	CNA record
openwebui open_webui openwebui:open_webui	from 0.9.2 before 0.10.0	NVD

References

References

https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw	x-refsource-confirm, exploit, mitigation, vendor-advisory
https://github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331	x-refsource-misc, patch
https://github.com/open-webui/open-webui/releases/tag/v0.10.0	x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.