AUGUST 4, 2026
Live Feed
Back to database
Case File

CVE-2021-33503

HIGH · CVSS 7.5 EPSS 3.27% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-06-29 · Last synced 2026-08-04

CyberRota Analysis

This is a high severity vulnerability with a CVSS score of 7.5. Public exploit code or proof-of-concept references have been detected in its references. It may lead to a denial-of-service condition.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-33503
Severity
HIGH
CVSS
7.5
EPSS
3.27%

Original NVD Description

An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking, causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.

Related CVEs

Other vulnerabilities affecting the same vendor(s)