cvedb.io
CVE-2025-43859
CRITICAL · CVSS 9.1
EPSS exploitation probability: 0%
Published 2025-04-24T19:15:47.060 · Last modified 2026-06-17T09:24:39.580

Summary

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.

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.