CVE-2026-39426— MaxKB: Stored XSS via Unsanitized iframe_render Parsing
Quick assessment
Affected
1Panel-dev MaxKB
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.
MaxKB是1Panel-dev开源的一款基于大语言模型和 RAG 的开源知识库问答系统。 MaxKB 2.7.1及之前版本存在跨站脚本漏洞，该漏洞源于前端MdRenderer.vue组件解析自定义iframe_render标签时绕过标准Markdown清理和XSS过滤，可能导致存储型跨站脚本攻击。
Possible ATT&CK Techniques 3 AI
T1071 · Application Layer Protocol T1059 · Command and Scripting Interpreter T1189 · Drive-by Compromise
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I. Basic Information for CVE-2026-39426
Vulnerability Information
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Vulnerability Title
MaxKB: Stored XSS via Unsanitized iframe_render Parsing
Source: CVE Program / CVE List V5
Vulnerability Description
MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a Stored Cross-Site Scripting (XSS) vulnerability where the frontend's MdRenderer.vue component parses custom <iframe_render> tags from LLM responses or Application Prologue configurations, bypassing standard Markdown sanitization and XSS filtering. The unsanitized HTML content is passed to the IframeRender.vue component, which renders it directly into an <iframe> via the srcdoc attribute configured with sandbox="allow-scripts allow-same-origin". This can be a dangerous combination, allowing injected scripts to escape the iframe and execute JavaScript in the parent window using window.parent. Since the Prologue is rendered for any user visiting an application's chat interface, this results in a high-impact Stored XSS that can lead to session hijacking, unauthorized actions, and sensitive data exposure. This issue has been fixed in version 2.8.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA: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
MaxKB 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MaxKB是1Panel-dev开源的一款基于大语言模型和 RAG 的开源知识库问答系统。 MaxKB 2.7.1及之前版本存在跨站脚本漏洞，该漏洞源于前端MdRenderer.vue组件解析自定义iframe_render标签时绕过标准Markdown清理和XSS过滤，可能导致存储型跨站脚本攻击。
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 |
|---|---|---|---|---|
| 1Panel-dev | MaxKB | < 2.8.0 | - |
|
II. Public POCs for CVE-2026-39426
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-39426 (1)
-
Release v2.8.0 · 1Panel-dev/MaxKB · GitHub x_refsource_MISC
Same Patch Batch · 1Panel-dev · 2026-04-14 · 10 CVEs total
| CVE-2026-39420 | 6.3 MEDIUM | MaxKB: Sandbox escape via LD_PRELOAD bypass |
| CVE-2026-39421 | 6.3 MEDIUM | MaxKB: Sandbox escape via ctypes and unhooked SYS_pkey_mprotect |
| CVE-2026-39418 | 5.0 MEDIUM | MaxKB: SSRF via sandbox network hook bypass |
| CVE-2026-39417 | 4.6 MEDIUM | MaxKB: RCE via MCP stdio command injection in workflow engine |
| CVE-2026-39419 | 3.1 LOW | MaxKB: Sandbox Result Validation Bypass via Tool Output Spoofing |
| CVE-2026-39424 | MaxKB has CSV Injection in its Application Chat Export Functionality | |
| CVE-2026-39423 | Stored XSS via Eval Injection in EchartsRander Component | |
| CVE-2026-39425 | MaxKB: Stored XSS via Unsanitized html_rander Tags in Markdown Rendering | |
| CVE-2026-39422 | MaxKB has Stored XSS via ChatHeadersMiddleware |
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V. Comments for CVE-2026-39426
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