CVE-2025-66418

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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub_MCNA
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CISA-ADPADP
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Base Score
CVSS 3.x
EPSS Score
Percentile: 9%
VendorProductVersion
pythonurllib3
1.24 ≤
𝑥
< 2.6.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
python-urllib3
bullseye
vulnerable
bullseye (security)
1.26.5-1~exp1+deb11u2
fixed
bookworm
vulnerable
bookworm (security)
1.26.12-1+deb12u2
fixed
trixie
vulnerable
trixie (security)
2.3.0-3+deb13u1
fixed
forky
2.5.0-2
fixed
sid
2.5.0-2
fixed
Common Weakness Enumeration
References
https://github.com/urllib3/urllib3/commit/24d7b67eac89f94e11003424bcf0d8f7b72222a8
https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53