CVE-2025-43859 | THREATINT

Description

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.

Reserved 2025-04-17 | Published 2025-04-24 | Updated 2025-04-24 | Assigner GitHub_M

CRITICAL: 9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem types

CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Product status

< 0.16.0

affected

References

github.com/...er/h11/security/advisories/GHSA-vqfr-h8mv-ghfj

github.com/...ommit/114803a29ce50116dc47951c690ad4892b1a36ed

cve.org (CVE-2025-43859)

nvd.nist.gov (CVE-2025-43859)

Download JSON