Medium severity · published Jul 9, 2026
CVE-2026-59220
Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
6.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 47% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OP
open-webui · open-webui
>= 0.9.2, < 0.10.0 · source: vendor
OW
Open Webui · Openwebui
0.9.2 before 0.10.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59220
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59220
Patch
https://github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331
Product
https://github.com/open-webui/open-webui/releases/tag/v0.10.0
Exploit
https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw
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