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
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | md-to-pdf | < 5.2.5 | 5.2.5 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H- Weakness (CWE)
CWE-94- Platform
- npm
- Package
md-to-pdf- Disclosed
- 20.11.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-547r-qmjm-8hvw - CC BY 4.0
Vulnerability history: md-to-pdf
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 12.2021 11.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
Disclosures per year
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 1
- 2026: 0
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