Threats affecting pkg:github/shd101wyy/vscode-markdown-preview-enhanced

Markdown Preview Enhanced for Visual Studio Code versions prior to 0.8.30 contains a cross-site scripting (XSS) vulnerability. The extension reads repository-controlled .crossnote/head.html content and inserts it into the preview webview's head without removing executable script content. This allows script execution before React and DOMPurify initialize, enabling malicious scripts to run when opening a Markdown preview in a malicious repository without further user interaction. The issue is fixed in version 0.8.30.

Markdown Preview Enhanced for Visual Studio Code prior to version 0.8.30 contains a vulnerability where the _crossnote.updateMarkdown command accepts arbitrary URIs and attacker-controlled content, allowing file writes without proper validation. This can be exploited by JavaScript executing in the preview webview to write files accessible by the user's OS privileges. The vulnerability is fixed in version 0.8.30.

Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.29, Markdown Preview Enhanced evaluates repository-controlled .crossnote/config.js and .crossnote/parser.js files with vm.runInNewContext, which does not provide a security boundary from the Node.js host realm. Opening a Markdown file in a malicious repository automatically loads these files, and prototype-chain traversal can reach the host Function constructor and process object, allowing operating-system commands to execute as the victim account without further interaction. Both configuration evaluation and parser-hook evaluation are affected, and the attack does not depend on module-scoped require being available. This issue is fixed in version 0.8.29.

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.