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Improper Control of Generation of Code ('Code Injection')

CVE-2026-41148

Medium
5.3/10

Summary

The state diagram and any other diagram type that routes user-controlled style strings through `createCssStyles` parser for Mermaid captures `classDef` values with an unrestricted regex: // packages/mermaid/src/diagrams/state/parser/stateDiagram.jison:83 <CLASSDEFID>[^\n]* { this.popState(); return 'CLASSDEF_STYLEOPTS' } The value passes unsanitized through `addStyleClass() -> createCssStyles() -> style.innerHTML` (mermaidAPI.ts:418). A } in the value closes the generated CSS selector, and everything after becomes a new CSS rule on the page. This issue affects mermaid versions prior to 10.9.6 and 11.x prior to 11.15.0.

  • LOW
  • NETWORK
  • PASSIVE
  • NONE

CWE-94 - Code Injection

Code injection is a type of vulnerability that allows an attacker to execute arbitrary code. This vulnerability fully compromises the machine and can cause a wide variety of security issues, such as unauthorized access to sensitive information, manipulation of data, denial of service attacks etc. Code injection is different from command injection in the fact that it is limited by the functionality of the injected language (e.g. PHP), as opposed to command injection, which leverages existing code to execute commands, usually within the context of a shell.

References

Advisory Timeline

  • Published