HTTP Request Smuggling Affecting mitmproxy package, versions <12.2.1-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.58% (45th percentile)

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  • Snyk IDSNYK-WOLFILATEST-MITMPROXY-15878610
  • published3 Apr 2026
  • disclosed24 Apr 2025

Introduced: 24 Apr 2025

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

How to fix?

Upgrade Wolfi mitmproxy to version 12.2.1-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream mitmproxy package and not the mitmproxy package as distributed by Wolfi. See How to fix? for Wolfi 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