Clipboard-based DOM-XSS

Vulnerability Description

@github/paste-markdown is an npm package for pasting markdown objects. A self Cross-Site Scripting vulnerability exists in the @github/paste-markdown before version 0.3.4. If the clipboard data contains the string `<table>`, a **div** is dynamically created, and the clipboard content is copied into its **innerHTML** property without any sanitization, resulting in improper execution of JavaScript in the browser of the victim (the user who pasted the code). Users directed to copy text from a malicious website and paste it into pages that utilize this library are affected. This is fixed in version 0.3.4. Refer the to the referenced GitHub Advisory for more details including an example exploit.

References

• https://github.com/github/paste-markdown/security/advisories/GHSA-gpfj-4j6g-c4w9
• https://github.com/github/paste-markdown/commit/32b7ea3f29ae8f256f9d19768387be42678ddf30
• https://github.com/github/paste-markdown/releases/tag/v0.3.4
• https://www.npmjs.com/package/%40github/paste-markdown