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Advisories

Markdown Preview Enhanced Arbitrary Code Execution via WaveDrom eval()

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severity
high
date
Affecting

  • Markdown Preview Enhanced >= 0, < 0.8.28

CWE
  • CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
CVSS
8.6
CVSS V4 Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Credit
Neo by ProjectDiscovery
Description
Markdown Preview Enhanced before 0.8.28 parses WaveDrom diagrams by evaluating untrusted markdown content with eval(), allowing arbitrary JavaScript execution. The flaw affects every render path - the live preview (window.eval) and presentation mode plus HTML export (the bundled WaveDrom.ProcessAll()/eva() helpers) - and can also be triggered through a <script type="WaveDrom"> element injected via raw HTML in markdown. When a victim previews or exports a crafted markdown document, an attacker can execute arbitrary code, leading to arbitrary file write. Fixed in 0.8.28 by parsing with JSON5.parse() and sanitizing WaveDrom data scripts to inert strict JSON.

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