CVE-2026-41149
Published:May 11, 2026
Updated:August 06, 2026
Impact Under the default configuration, Mermaid state diagram's "classDef" allow DOM injection that escapes the SVG, although "<script>" tags are removed, preventing XSS. Proof-of-concept stateDiagram-v2 classDef xss fill:red</style></svg><style>{x:x;y:y;overflow:visible!important;contain:none!important;transform:none!important;filter:none!important;clip-path:none!important}</style><div style="x:x;y:y;color:red;font:5em/1 monospace;display:grid;place-items:center;z-index:2147483647;width:100vw;height:100vh;position:fixed;top:0;left:0;background:black">HACKED</div><svg><style>a:b [] --> A:::xss Patches - "v11.15.0" (https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0) (see "37ff937f1da2e19f882fd1db01235db4d01f4056" (https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056)) - "v10.9.6" (https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6) (see "4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3" (https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3)) Workarounds If you can not update to a patched version, setting """securityLevel": "sandbox""" (https://mermaid.js.org/config/schema-docs/config.html#securitylevel) will prevent this, by rendering the mermaid diagram in a sandboxed "<iframe>". Credits Thanks to @zsxsoft from @KeenSecurityLab for reporting this vulnerability.
Affected Packages
mermaid (CDN_JS):
Affected version(s) >=11.0.0-alpha.1 <11.15.0Fix Suggestion:
Update to version 11.15.0mermaid (CDN_JS):
Affected version(s) >=0.1.0 <10.9.6Fix Suggestion:
Update to version 10.9.6https://github.com/mermaid-js/mermaid.git (GITHUB):
Affected version(s) >=mermaid@11.0.1 <mermaid@11.15.0Fix Suggestion:
Update to version mermaid@11.15.0https://github.com/mermaid-js/mermaid.git (GITHUB):
Affected version(s) >=v10.9.0 <v10.9.6Fix Suggestion:
Update to version v10.9.6mermaid (NPM):
Affected version(s) >=0.2.11 <10.9.6Fix Suggestion:
Update to version 10.9.6mermaid (NPM):
Affected version(s) >=11.0.0-alpha.1 <11.15.0Fix Suggestion:
Update to version 11.15.0Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
LOW
Subsequent System Integrity
LOW
Subsequent System Availability
LOW
CVSS v3
Base Score:
4.7
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Improper Control of Generation of Code ('Code Injection')
EPSS
Base Score:
0.40