Affected: AlmaLinux:10: python3-urllib3

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

* urllib3: urllib3: Unbounded decompression chain leads to resource exhaustion (CVE-2025-66418) * urllib3: urllib3 Streaming API improperly handles highly compressed data (CVE-2025-66471) * urllib3: urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API) (CVE-2026-21441)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Affected: Alpaquita:23: py3-urllib3, Alpaquita:25: py3-urllib3, Alpaquita:stream: py3-urllib3

Affected: Homebrew: abi3audit

### Impact

urllib3's [streaming API](https://urllib3.readthedocs.io/en/2.5.0/advanced-usage.html#streaming-and-i-o) 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; CWE-409) on the client side, even if the application only requested a small chunk of data.

### Affected usages

Applications and libraries using urllib3 version 2.5.0 and earlier to stream large compressed responses or content from untrusted sources.

`stream()`, `read(amt=256)`, `read1(amt=256)`, `read_chunked(amt=256)`, `readinto(b)` are examples of `urllib3.HTTPResponse` method calls using the affected logic unless decoding is disabled explicitly.

### Remediation

Upgrade to at least urllib3 v2.6.0 in which the library avoids decompressing data tha…

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.

Affected: PyPI: urllib3

### Impact

urllib3's [streaming API](https://urllib3.readthedocs.io/en/2.5.0/advanced-usage.html#streaming-and-i-o) 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; CWE-409) on the client side, even if the application only requested a small chunk of data.

### Affected usages

Applications and libraries using urllib3 version 2.5.0 and earlier to stream large compressed responses or content from untrusted sources.

`stream()`, `read(amt=256)`, `read1(amt=256)`, `read_chunked(amt=256)`, `readinto(b)` are examples of `urllib3.HTTPResponse` method calls using the affected logic unless decoding is disabled explicitly.

### Remediation

Upgrade to at least urllib3 v2.6.0 in which the library avoids decompressing data tha…

Affected: openEuler:24.03-LTS-SP1: python-urllib3

HTTP library with thread-safe connection pooling, file post support, sanity friendly, and more. Security Fix(es):

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)

Recommended update for python-urllib3

Affected: PyPI: urllib3

### Impact

urllib3's [streaming API](https://urllib3.readthedocs.io/en/2.5.0/advanced-usage.html#streaming-and-i-o) 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; CWE-409) on the client side, even if the application only requested a small chunk of data.

### Affected usages

Applications and libraries using urllib3 version 2.5.0 and earlier to stream large compressed responses or content from untrusted sources.

`stream()`, `read(amt=256)`, `read1(amt=256)`, `read_chunked(amt=256)`, `readinto(b)` are examples of `urllib3.HTTPResponse` method calls using the affected logic unless decoding is disabled explicitly.

### Remediation

Upgrade to at least urllib3 v2.6.0 in which the library avoids decompressing data tha…

crypto/x509: golang: Denial of Service due to excessive resource consumption via crafted certificate urllib3: urllib3 Streaming API improperly handles highly compressed data urllib3: urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API)

Recommended update for python-urllib3

Affected: Ubuntu:Pro:14.04:LTS: python-pip, Ubuntu:Pro:14.04:LTS: python-urllib3, Ubuntu:Pro:16.04:LTS: python-urllib3, Ubuntu:Pro:16.04:LTS: python-pip, Ubuntu:Pro:18.04:LTS: python-urllib3, Ubuntu:Pro:18.04:LTS: python-pip, Ubuntu:Pro:20.04:LTS: python-urllib3, Ubuntu:Pro:20.04:LTS: python-pip, Ubuntu:22.04:LTS: python-urllib3, Ubuntu:Pro:22.04:LTS: python-pip and 6 more

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.

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in NetApp ActiveIQ Unified Manager ausnutzen, um einen Denial of Service Angriff durchzuführen.