CVE-2025-66418

CVE Details

Release Date:	2025-12-05
Impact:	Important	What is this?

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.

See more information about CVE-2025-66418 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	7.5
Vector String:	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Version:	3.1
Attack Vector:	Network
Attack Complexity:	Low
Privileges Required:	None
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	None
Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 10 (python-urllib3)	ELSA-2026-1086	2026-01-26
Oracle Linux version 8 (fence-agents)	ELSA-2026-1240	2026-01-27
Oracle Linux version 8 (python-urllib3)	ELSA-2026-1254	2026-01-26
Oracle Linux version 8 (python3.11-urllib3)	ELSA-2026-1224	2026-01-26
Oracle Linux version 8 (python3.12-urllib3)	ELSA-2026-1226	2026-01-26
Oracle Linux version 8 (resource-agents)	ELSA-2026-1241	2026-01-26
Oracle Linux version 9 (fence-agents)	ELSA-2026-1239	2026-01-27
Oracle Linux version 9 (python-urllib3)	ELSA-2026-1087	2026-01-26
Oracle Linux version 9 (python3.11-urllib3)	ELSA-2026-1089	2026-01-26
Oracle Linux version 9 (python3.12-urllib3)	ELSA-2026-1088	2026-01-26