CVE-2025-43859
CVSS 3.1 Score 9.1 of 10 (high)
Details
Published Apr 24, 2025
Updated: Apr 29, 2025
CWE ID 444
Summary
CVE-2025-43859 affects the Python implementation of HTTP/1.1 named h11. The vulnerability arises from h11's lenient parsing of line terminators in chunked-coding message bodies, which can result in request smuggling under specific conditions. Exploitation of this issue requires both a buggy h11 and a susceptible (reverse) proxy, making it dependent on both components. Version 0.16.0 of h11 has been released with the necessary patch to mitigate this vulnerability.
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Affected Products
- python-hyper H11