Allocation of Resources Without Limits or Throttling Affecting python3-urllib3 package, versions <0:1.25.6-2.amzn2.0.4


Severity

Recommended
medium

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.69% (50th percentile)

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  • Snyk IDSNYK-AMZN2-PYTHON3URLLIB3-15058247
  • published22 Jan 2026
  • disclosed5 Dec 2025

Introduced: 5 Dec 2025

CVE-2025-66418  (opens in a new tab)
CWE-770  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2 python3-urllib3 to version 0:1.25.6-2.amzn2.0.4 or higher.
This issue was patched in ALAS2-2026-3127.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3-urllib3 package and not the python3-urllib3 package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1