CVE-2025-66418
python-urllib3 - security update
7.5
HIGH
CVSS 3.1
EPSS 0.02%
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.
How to fix CVE-2025-66418
To remediate CVE-2025-66418, upgrade the affected package to a fixed version below.
- —upgrade to 2.6.3-r0 or later
- —upgrade to 1.26.5-1~exp1+deb11u2 or later
- —upgrade to 1.26.12-1+deb12u2 or later
- —upgrade to 2.6.0 or later
Is CVE-2025-66418 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- from 0, < 2.6.3-r0
- from 0, < 1.26.5-1~exp1+deb11u2
- from 0, < 1.26.12-1+deb12u2
- >= 1.24, < 2.6.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |