CVE-2025-43859 – h11 accepts some malformed Chunked-Encoding bodies

https://notcve.org/view.php?id=CVE-2025-43859

24 Apr 2025 — h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue. A flaw was found in the h11. • https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj • CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') •