HTTP Request Smuggling Affecting python-h11 package, versions <0.14.0-1.1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.03% (8th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-PYTHONH11-9812620
  • published26 Apr 2025
  • disclosed24 Apr 2025

Introduced: 24 Apr 2025

NewCVE-2025-43859  (opens in a new tab)
CWE-444  (opens in a new tab)

How to fix?

Upgrade Debian:unstable python-h11 to version 0.14.0-1.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python-h11 package and not the python-h11 package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1