https://vulnerability.circl.lu/rss/recent/all/10 Most recent entries from all 2026-09-29T15:39:05.735133+00:00 Vulnerability-Lookup info@circl.lu python-feedgen Contains only the most 10 recent entries. https://vulnerability.circl.lu/vuln/cve-2025-66418 CVE-2025-66418 — urllib3 allows an unbounded number of links in the decompression chain 2026-09-29T15:39:05.741711+00:00

Affected: urllib3

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.

 https://vulnerability.circl.lu/vuln/ghsa-gm62-xv2j-4w53 GHSA-gm62-xv2j-4w53 — urllib3 allows an unbounded number of links in the decompression chain 2026-09-29T15:39:05.741829+00:00

Affected: PyPI: urllib3

## Impact

urllib3 supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., `Content-Encoding: gzip, zstd`).

However, 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.

## Affected usages

Applications and libraries using urllib3 version 2.5.0 and earlier for HTTP requests to untrusted sources unless they disable content decoding explicitly.

## Remediation

Upgrade to at least urllib3 v2.6.0 in which the library limits the number of links to 5.

If upgrading is not immediately possible, use [`preload_content=False`](https://urllib3.readthedocs.io/en/2.5.0/advanced-usage.html#streaming-and-i-o) and ensure that `resp.headers["content-encoding"]` contains a safe number of encodings before reading the response content.

 https://vulnerability.circl.lu/vuln/pysec-2026-1998 PYSEC-2026-1998 — urllib3 allows an unbounded number of links in the decompression chain 2026-09-29T15:39:05.741901+00:00

Affected: PyPI: urllib3

## Impact

urllib3 supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., `Content-Encoding: gzip, zstd`).

However, 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.

## Affected usages

Applications and libraries using urllib3 version 2.5.0 and earlier for HTTP requests to untrusted sources unless they disable content decoding explicitly.

## Remediation

Upgrade to at least urllib3 v2.6.0 in which the library limits the number of links to 5.

If upgrading is not immediately possible, use [`preload_content=False`](https://urllib3.readthedocs.io/en/2.5.0/advanced-usage.html#streaming-and-i-o) and ensure that `resp.headers["content-encoding"]` contains a safe number of encodings before reading the response content.