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CVE-2026-41149— Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection

Quick assessment

Affected
mermaid-js mermaid
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.

Mermaid是mermaid-js开源的一个应用软件。使用文本和代码创建图表和可视化。 Mermaid 10.9.5及之前版本和11.0.0-alpha.1版本至11.14.0版本存在安全漏洞，该漏洞源于默认配置下的HTML注入，可能导致DOM注入。

AI Predicted 6.1 Difficulty: Easy EPSS 0.52% · P42

Possible ATT&CK Techniques 1 AI

T1189 · Drive-by Compromise

Affected Version Matrix 2

VendorProduct Version RangeStatus
mermaid-js mermaid >= 11.0.0-alpha.1, < 11.15.0 affected
< 10.9.6 affected
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I. Basic Information for CVE-2026-41149

Vulnerability Information
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Vulnerability Title
Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection
Source: CVE Program / CVE List V5
Vulnerability Description
Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Versions 10.9.5 and earlier, as well as 11.0.0-alpha.1 through 11.14.0, are vulnerable to HTML injection under the default configuration. Specifically, the classDef directive in Mermaid state diagrams permits DOM injection that escapes the SVG context. However, <script> tags are stripped, which prevents cross-site scripting (XSS). This issue has been fixed in versions 10.9.6 and 11.15.0. If developers are unable to immediately upgrade, they can work around this issue by setting "securityLevel": "sandbox", which prevents the issue by rendering the mermaid diagram in a sandboxed <iframe>.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L
Source: CVE Program / CVE List V5
Vulnerability Type
对生成代码的控制不恰当(代码注入)
Source: CVE Program / CVE List V5
Vulnerability Title
Mermaid 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mermaid是mermaid-js开源的一个应用软件。使用文本和代码创建图表和可视化。 Mermaid 10.9.5及之前版本和11.0.0-alpha.1版本至11.14.0版本存在安全漏洞，该漏洞源于默认配置下的HTML注入，可能导致DOM注入。
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
mermaid-js mermaid >= 11.0.0-alpha.1, < 11.15.0 -

II. Public POCs for CVE-2026-41149

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III. Intelligence Information for CVE-2026-41149

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Patches & Fixes for CVE-2026-41149 (2)

Vendor Advisories for CVE-2026-41149 (1)

IV. Related Vulnerabilities

Same product: mermaid
Same vendor: mermaid-js
Same weakness: CWE-94

V. Comments for CVE-2026-41149

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