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.
References (2)
Core 2
Core References
Vendor Advisory x_refsource_confirm
https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53
Scores
CVSS v3
7.5
EPSS
0.0002
EPSS Percentile
5.8%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-770
Status
published
Products (2)
pypi/urllib3
1.24 - 2.6.0PyPI
python/urllib3
1.24 - 2.6.0
Published
Dec 05, 2025
Tracked Since
Feb 18, 2026