CVE-2026-41149: CWE-94: Improper Control of Generation of Code ('Code Injection') in mermaid-js mermaid
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>.
AI Analysis
Technical Summary
CVE-2026-41149 is an improper control of code generation vulnerability (CWE-94) in the mermaid-js mermaid tool. The vulnerability arises from the classDef directive in state diagrams allowing DOM injection that escapes the SVG context, leading to HTML injection. Although <script> tags are removed, preventing direct cross-site scripting, the injection could still affect the DOM. Affected versions include all versions up to 10.9.5 and from 11.0.0-alpha.1 up to but not including 11.15.0. The vulnerability has been addressed in versions 10.9.6 and 11.15.0. Developers unable to upgrade immediately can mitigate the issue by enabling the "securityLevel": "sandbox" setting, which confines rendering to a sandboxed iframe.
Potential Impact
The vulnerability allows HTML injection through the classDef directive, which can lead to DOM manipulation outside the SVG context. While direct script injection is prevented by stripping <script> tags, the injection could still affect the integrity of the rendered content. The CVSS 4.0 score is 5.3 (medium severity), indicating a moderate risk with network attack vector, no privileges required, and user interaction needed.
Mitigation Recommendations
A fix is available in mermaid versions 10.9.6 and 11.15.0. Users should upgrade to these or later versions to remediate the vulnerability. If immediate upgrading is not feasible, setting the configuration option "securityLevel" to "sandbox" provides a temporary workaround by rendering diagrams in a sandboxed iframe, preventing the injection issue.
CVE-2026-41149: CWE-94: Improper Control of Generation of Code ('Code Injection') in mermaid-js mermaid
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>.
CVSS v4.0
Score 5.3medium
Affected software
pkg:npm/mermaid-js/mermaidRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-41149 is an improper control of code generation vulnerability (CWE-94) in the mermaid-js mermaid tool. The vulnerability arises from the classDef directive in state diagrams allowing DOM injection that escapes the SVG context, leading to HTML injection. Although <script> tags are removed, preventing direct cross-site scripting, the injection could still affect the DOM. Affected versions include all versions up to 10.9.5 and from 11.0.0-alpha.1 up to but not including 11.15.0. The vulnerability has been addressed in versions 10.9.6 and 11.15.0. Developers unable to upgrade immediately can mitigate the issue by enabling the "securityLevel": "sandbox" setting, which confines rendering to a sandboxed iframe.
Potential Impact
The vulnerability allows HTML injection through the classDef directive, which can lead to DOM manipulation outside the SVG context. While direct script injection is prevented by stripping <script> tags, the injection could still affect the integrity of the rendered content. The CVSS 4.0 score is 5.3 (medium severity), indicating a moderate risk with network attack vector, no privileges required, and user interaction needed.
Mitigation Recommendations
A fix is available in mermaid versions 10.9.6 and 11.15.0. Users should upgrade to these or later versions to remediate the vulnerability. If immediate upgrading is not feasible, setting the configuration option "securityLevel" to "sandbox" provides a temporary workaround by rendering diagrams in a sandboxed iframe, preventing the injection issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-17T12:59:15.739Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a10dcbfe1370fbb485f73b4
Added to database: 05/22/2026, 22:46:23 UTC
Last enriched: 05/22/2026, 22:59:46 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 108
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