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

Quick assessment

Affected
open-webui open-webui
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Open WebUI是Open WebUI团队开源的一个可扩展、功能丰富、用户友好的自托管 WebUI。 Open WebUI 0.10.0之前版本（且不低于0.9.2版本）存在资源管理错误漏洞，该漏洞源于正则表达式（SKILL_MENTION_RE和strip_re）存在重叠量词，允许经过身份验证的聊天消息包含 且无关闭 的字符序列，触发二次回溯并阻塞asyncio事件循环。

CVSS 6.5 · Medium EPSS 0.57% · P45

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
open-webui open-webui >= 0.9.2, < 0.10.0 affected
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I. Basic Information for CVE-2026-59220

Vulnerability Information
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Vulnerability Title
Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1333
Source: CVE Program / CVE List V5
Vulnerability Title
Open WebUI 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Open WebUI是Open WebUI团队开源的一个可扩展、功能丰富、用户友好的自托管 WebUI。 Open WebUI 0.10.0之前版本（且不低于0.9.2版本）存在资源管理错误漏洞，该漏洞源于正则表达式（SKILL_MENTION_RE和strip_re）存在重叠量词，允许经过身份验证的聊天消息包含`<$`且无关闭`>`的字符序列，触发二次回溯并阻塞asyncio事件循环。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
open-webui open-webui >= 0.9.2, < 0.10.0 -

II. Public POCs for CVE-2026-59220

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III. Intelligence Information for CVE-2026-59220

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Vendor Advisories for CVE-2026-59220 (1)

Vendor Pages for CVE-2026-59220 (1)

Same Patch Batch · open-webui · 2026-07-09 · 17 CVEs total

CVE-2026-59224 8.0 HIGH Open WebUI: Terminal proxy forwards a spoofable, integrity-unbound user identity to the up
CVE-2026-59216 7.7 HIGH Open WebUI: Cross-user code-interpreter and tool execution via unvalidated Socket.IO event
CVE-2026-59221 7.7 HIGH open-webui terminal proxy path traversal guard bypass via 9x encoded traversal
CVE-2026-59214 7.3 HIGH Open WebUI: Stored web worker XSS via Pyodide
CVE-2026-59219 7.1 HIGH Open WebUI: Realtime endpoints accept Redis-revoked JWTs after signout/backchannel logout
CVE-2026-59212 5.4 MEDIUM Open WebUI: Model meta.knowledge read-only file access can be upgraded to file write/delet
CVE-2026-59225 5.4 MEDIUM Open WebUI: Arena task endpoints can bypass underlying model access controls
CVE-2026-59218 5.3 MEDIUM Open WebUI: Account enumeration via observable login timing discrepancy
CVE-2026-59227 4.3 MEDIUM Open WebUI: POST /api/v1/images/edit bypasses the global image-edit switch and the per-use
CVE-2026-59217 4.3 MEDIUM Open WebUI: Upload `metadata.knowledge_id` bypasses the knowledge-base write-access check
CVE-2026-59223 4.3 MEDIUM Open WebUI: `WEB_FETCH_FILTER_LIST` host allow/block filter bypassable via URL path and no
CVE-2026-59213 3.5 LOW Open WebUI: Cross-user model-list exposure via static cache key in get_all_models (aiocach
CVE-2026-59226 3.1 LOW Open WebUI: Scheduled automations continue after pending-user deactivation and stored mode
CVE-2026-59715 3.1 LOW Open WebUI: Unauthenticated WebSocket Access to Collaborative Document Handlers (ydoc:awar
CVE-2026-59215 3.1 LOW Open WebUI: Private channel messages can be disclosed through cross-channel thread parent_
CVE-2026-59222 Open WebUI: /api/v1/channels/{id}/members exposes full user model including sensitive cred

IV. Related Vulnerabilities

Same product: open-webui
Same vendor: open-webui
Same weakness: CWE-1333

V. Comments for CVE-2026-59220

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