#VU121072 Improper handling of highly compressed data in urllib3 - CVE-2026-21441
Published: January 7, 2026 / Updated: February 17, 2026
Vulnerability identifier: #VU121072
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-21441
CWE-ID: CWE-409
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
urllib3
urllib3
Software vendor:
shazow (Andrey Petrov)
shazow (Andrey Petrov)
Description
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to the application does not properly handle highly compressed data when sending HTTP redirect responses. A remote attacker can multiple large requests to the application, consume all available CPU and memory resources and perform a denial of service attack.
Remediation
Install updates from vendor's website.