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.
History

Tue, 29 Apr 2025 03:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Thu, 24 Apr 2025 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 24 Apr 2025 18:30:00 +0000

Type Values Removed Values Added
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.
Title h11 accepts some malformed Chunked-Encoding bodies
Weaknesses CWE-444
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2025-04-24T18:15:53.328Z

Updated: 2025-04-24T19:02:45.130Z

Reserved: 2025-04-17T20:07:08.556Z

Link: CVE-2025-43859

cve-icon Vulnrichment

Updated: 2025-04-24T19:02:18.751Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-04-24T19:15:47.060

Modified: 2025-04-29T13:52:28.490

Link: CVE-2025-43859

cve-icon Redhat

Severity : Important

Publid Date: 2025-04-24T18:15:53Z

Links: CVE-2025-43859 - Bugzilla