CVE-2026-59220

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

MEDIUM
6.5
CVSS Score
Published: July 9, 2026 at 04:09 PM UTC
Updated: July 10, 2026 at 06:28 PM UTC
1 product affected across 1 vendorOpen Webui

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.6%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.10.00.9.2 ≤ v < 0.10.0
Affected range stops below 0.10.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

x_refsource_CONFIRMExploitMitigationVendor Advisory
Source: cverecord
https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw
x_refsource_MISCProductRelease Notes
Source: cverecord
https://github.com/open-webui/open-webui/releases/tag/v0.10.0

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-1333

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