md-to-pdf vulnerable to arbitrary JavaScript code execution when parsing front matter

### 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

Source published

20 Nov 2025 17:48:11 UTC

Source modified

25 Nov 2025 19:48:40 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Publisher rating · CRITICAL