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CVE-2026-54011— Open WebUI: Stored XSS in Mermaid Markdown Preview

Quick assessment

Affected
open-webui open-webui
Exploitation
Public or AI PoC available; prioritize validation
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 0.9.6之前版本存在跨站脚本漏洞，该漏洞源于应用在处理Markdown文件预览时，使用innerHTML将Mermaid生成的SVG插入DOM，且Mermaid配置了宽松的安全等级，导致攻击者控制的Mermaid内容不安全渲染，可能造成在受害者浏览器中执行JavaScript脚本。

CVSS 8.7 · High EPSS 0.23% · P14

Affected Version Matrix 1

VendorProduct Version RangeStatus
open-webui open-webui < 0.9.6 affected
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I. Basic Information for CVE-2026-54011

Vulnerability Information
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Vulnerability Title
Open WebUI: Stored XSS in Mermaid Markdown Preview
Source: CVE Program / CVE List V5
Vulnerability Description
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6,Open WebUI renders Mermaid blocks from Markdown files in the file preview panel and inserts the generated SVG into the DOM using innerHTML. Because Mermaid is configured with securityLevel: 'loose', attacker-controlled Mermaid content can be rendered unsafely in this flow. A working payload was validated through the Markdown preview path, resulting in JavaScript execution in the victim’s browser under the application origin. This vulnerability is fixed in 0.9.6.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
Open WebUI 跨站脚本漏洞
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 0.9.6之前版本存在跨站脚本漏洞，该漏洞源于应用在处理Markdown文件预览时，使用innerHTML将Mermaid生成的SVG插入DOM，且Mermaid配置了宽松的安全等级，导致攻击者控制的Mermaid内容不安全渲染，可能造成在受害者浏览器中执行JavaScript脚本。
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 < 0.9.6 -

II. Public POCs for CVE-2026-54011

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 5308 chars
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III. Intelligence Information for CVE-2026-54011

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Vendor Advisories for CVE-2026-54011 (1)

Same Patch Batch · open-webui · 2026-06-23 · 15 CVEs total

CVE-2026-54008 8.5 HIGH Open WebUI: Redirect-Bypass SSRF in OAuth `_process_picture_url`
CVE-2026-54010 8.3 HIGH Open WebUI: Forged chat-file link allows cross-user file read and deletion
CVE-2026-54018 7.7 HIGH Open WebUI: SSRF Protection Bypass in Playwright Web Loader via HTTP Redirects
CVE-2026-54013 7.6 HIGH Open WebUI: Stored XSS to Account Takeover via Model Profile Images in Open WebUI
CVE-2026-54012 7.1 HIGH Open WebUI: Forged model meta.knowledge allows cross-user file read and deletion
CVE-2026-54009 6.5 MEDIUM Open WebUI: Cross-user file disclosure via /api/chat/completions image_url field
CVE-2026-54019 6.5 MEDIUM Open WebUI: RAG ACL Bypass in Milvus Multitenancy Mode
CVE-2026-54015 6.4 MEDIUM Open WebUI: Prompt history IDOR: unbound history_id allows cross-prompt read and deletion
CVE-2026-54021 6.3 MEDIUM Open WebUI: Authenticated users can target arbitrary configured Ollama backends via unguar
CVE-2026-54022 5.3 MEDIUM Open WebUI: Any authenticated user can read other users' private notes via Socket.IO
CVE-2026-54016 4.3 MEDIUM Open WebUI: Open WebUI BOLA: `search_knowledge_files` Allows Unauthorized Knowledge Base F
CVE-2026-54006 4.3 MEDIUM Open WebUI: Calendar event re-parenting allows writing events into another user's calendar
CVE-2026-54014 4.3 MEDIUM Open WebUI: Sibling-Prefix Path Traversal via /cache/{path} in open-webui/open-webui
CVE-2026-54007 Open WebUI: Cross-origin postMessage confirmation bypass via action:submit

IV. Related Vulnerabilities

Same product: open-webui
Same vendor: open-webui
Same weakness: CWE-79

V. Comments for CVE-2026-54011

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