Improper Handling of Highly Compressed Data (Data Amplification) Affecting python-urllib3 package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN13-PYTHONURLLIB3-14193375
- published6 Dec 2025
- disclosed5 Dec 2025
Introduced: 5 Dec 2025
NewCVE-2025-66471 (opens in a new tab)How to fix?
There is no fixed version for Debian:13 python-urllib3.
NVD Description
Note: Versions mentioned in the description apply only to the upstream python-urllib3 package and not the python-urllib3 package as distributed by Debian.
See How to fix? for Debian:13 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.