Improper Handling of Highly Compressed Data (Data Amplification) Affecting rhcos package, versions *


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.03% (7th percentile)

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  • Snyk IDSNYK-RHEL9-RHCOS-15046832
  • published21 Jan 2026
  • disclosed5 Dec 2025

Introduced: 5 Dec 2025

CVE-2025-66471  (opens in a new tab)
CWE-409  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 rhcos.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rhcos package and not the rhcos package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1