md-to-pdf is a CLI tool for converting Markdown files to PDF using Node.js and headless Chrome. Prior to version 5.2.5, a Markdown front-matter block that contains JavaScript delimiter causes the JS engine in gray-matter library to execute arbitrary code in the Markdown to PDF converter process of md-to-pdf library, resulting in remote code execution. This issue has been patched in version 5.2.5.

Affected: npm: md-to-pdf

### Summary A Markdown front-matter block that contains JavaScript delimiter causes the JS engine in gray-matter library to execute arbitrary code in the Markdown to PDF converter process of **md-to-pdf** library, resulting in remote code execution.

### Details **md-to-pdf** uses the gray-matter library to parse front-matter. Gray-matter exposes a JavaScript engine that, when enabled or triggered by certain front-matter delimiters (e.g. ---js or ---javascript), will evaluate the front-matter contents as JavaScript. If user-supplied Markdown is fed to md-to-pdf and the front-matter contains malicious JS, the converter process will execute that code.

### PoC ``` const { mdToPdf } = require('md-to-pdf');

var payload = '---javascript\n((require("child_process")).execSync("calc.exe"))\n---RCE';

(async () => { await mdToPdf({ content: payload }, { dest: './output.pdf'}); })(); ``` Running the PoC on Windows launches the calculator application, demonstrating arbitrary code execution.

### Impact

- Remote code execution in the process that performs Markdown->PDF conversion. - If the converter is run in a web app or cloud service, an attacker uploading malicious Markdown can execute arbitrary commands on the