CVE-2021-33502: Normalize-Url Project Normalize-Url

High severity, CVSS 7.5. EPSS: 1.7% chance of exploitation in the next 30 days.

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.

Affected products

• Normalize-Url Project Normalize-Url: from 4.3.0, before 4.5.1 (fixed in 4.5.1); from 5.0.0, before 5.3.1 (fixed in 5.3.1); version 6.0.0 only

Published 2021-05-24. Last modified 2026-06-17.