Detections
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Alpine: py3-urllib3: security update to 2.6.3-r0
high Tenable Self-Hosted Container Security Plugin ID 436916
Description
There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:- 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. (CVE-2025-66418)
- 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. (CVE-2025-66471)
- urllib3 is an HTTP client library for Python. 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. urllib3 can perform decoding or decompression based on the HTTP `Content-
Encoding` header (e.g., `gzip`, `deflate`, `br`, or `zstd`). When using the streaming API, the library
decompresses only the necessary bytes, enabling partial content consumption. Starting in version 1.22 and
prior to version 2.6.3, for HTTP redirect responses, the library would read the entire response body to
drain the connection and decompress the content unnecessarily. This decompression occurred even before any
read methods were called, and configured read limits did not restrict the amount of decompressed data. As
a result, there was no safeguard against decompression bombs. A malicious server could exploit this to
trigger excessive resource consumption on the client. Applications and libraries are affected when they
stream content from untrusted sources by setting `preload_content=False` when they do not disable
redirects. Users should upgrade to at least urllib3 v2.6.3, in which the library does not decode content
of redirect responses when `preload_content=False`. If upgrading is not immediately possible, disable
redirects by setting `redirect=False` for requests to untrusted source. (CVE-2026-21441)
See Also
https://security.alpinelinux.org/vuln/CVE-2025-66418
Plugin Details
Severity: High
ID: 436916
Version: Revision 1.5
Type: Local
Published: 1/24/2026
Updated: 5/22/2026
Supported Sensors: Agentless Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security
Risk Information
VPR
Risk Factor: Medium
Score: 5.7
Percentile: 96.49
CVSS v2
Risk Factor: High
Base Score: 7.8
Temporal Score: 5.8
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C
CVSS Score Source: CVE-2026-21441
CVSS v3
Risk Factor: High
Base Score: 7.5
Temporal Score: 6.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
CVSS v4
Risk Factor: High
Base Score: 8.9
Threat Score: 6.3
Threat Vector: CVSS:4.0/E:U
Vector: 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
Vulnerability Information
Exploit Ease: No known exploits are available
Vulnerability Publication Date: 12/5/2025