Markdown Preview Enhanced 0.8.x Code Injection via WaveDrom Rendering

Markdown Preview Enhanced 0.8.x with crossnote engine 0.9.28 contains a code injection vulnerability in the WaveDrom rendering pipeline that allows attackers to execute arbitrary JavaScript by embedding malicious content in a wavedrom fenced code block within a crafted Markdown document. Attackers can exploit the unsanitized passing of wavedrom block content to window.eval() in the VS Code webview context to abuse the extension's message passing and invoke arbitrary file writes on the local filesystem.

Markdown Preview Enhanced OS Command Injection in External File and Link Opening

Markdown Preview Enhanced before 0.8.28 opens external files and links from the preview through a shell and does not validate untrusted inputs taken from the markdown document - the diagram filename attribute, imported file paths, and the latex_engine code-chunk attribute. On Windows, a crafted markdown document can inject operating system commands that execute when the document is previewed. Fixed in 0.8.28 by passing these inputs as literal arguments instead of through a shell and validating them before use.

Markdown Preview Enhanced Arbitrary Code Execution via WaveDrom eval()

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.

An issue in Visual Studio Code Extensions Markdown Preview Enhanced v0.8.18 allows attackers to execute arbitrary code via uploading a crafted .Md file.