VULNERABILITY INTELLIGENCE

CVE-2025-66418

CVSS score7.5 HIGH
EPSS probability0.68%
CISA KEVNot currently listed
Published2025-12-05
Last modified2026-09-25
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Description

urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

Weakness classification

  • security-advisories@github.com: CWE-770

Primary references