- Description
- urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.0 and prior to 2.6.0, the Streaming API improperly handles highly compressed data. urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When streaming a compressed response, urllib3 can perform decoding or decompression based on the HTTP Content-Encoding header (e.g., gzip, deflate, br, or zstd). The library must read compressed data from the network and decompress it until the requested chunk size is met. Any resulting decompressed data that exceeds the requested amount is held in an internal buffer for the next read operation. The decompression logic could cause urllib3 to fully decode a small amount of highly compressed data in a single operation. This can result in excessive resource consumption (high CPU usage and massive memory allocation for the decompressed data.
- Source
- security-advisories@github.com
- NVD status
- Analyzed
- Products
- urllib3
CVSS 4.0
- Type
- Secondary
- Base score
- 8.9
- Impact score
- -
- Exploitability score
- -
- Vector string
- 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Severity
- HIGH
CVSS 3.1
- Type
- Primary
- Base score
- 7.5
- Impact score
- 3.6
- Exploitability score
- 3.9
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Severity
- HIGH
- security-advisories@github.com
- CWE-409
- Hype score
- Not currently trending
🛡️ #DevOps Alert! Two new vulnerabilities (CVE-2025-66418 & CVE-2025-66471) in python-urllib3 are putting #SUSE Linux Micro 6.1 systems at risk. Read mroe: 👉 https://t.co/yj5aMbHKfU #Security https://t.co/WvJEFtGpJV
@Cezar_H_Linux
27 Feb 2026
44 Impressions
0 Retweets
0 Likes
0 Bookmarks
0 Replies
0 Quotes
Urgent: #openSUSE Leap 16.0 security update for python-urllib3 fixes 3 DoS flaws (CVE-2025-66471, CVE-2025-66418, CVE-2026-21441). Read more: 👉 https://t.co/9VHYKIbhsI #Security #Linux https://t.co/q4gKPJWZxz
@Cezar_H_Linux
27 Feb 2026
49 Impressions
0 Retweets
0 Likes
0 Bookmarks
0 Replies
0 Quotes
URGENT: #Fedora 42 Brotli update (v1.2.0) patches critical DoS vulnerabilities CVE-2025-66471 & CVE-2025-6176. Read more: 👉 https://t.co/EINelVuIhT #Security https://t.co/9r1feUTgcr
@Cezar_H_Linux
18 Dec 2025
58 Impressions
0 Retweets
0 Likes
0 Bookmarks
0 Replies
0 Quotes
[
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*",
"matchCriteriaId": "2196EB74-E1B9-4BD0-96B6-9477225D385D",
"versionEndExcluding": "2.6.0",
"versionStartIncluding": "1.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
]