Security Advisory

CVE-2026-71554

CVE vulnerability detail - eXtreme Datacenter Security Operations

Published 2026-08-06 21:46:43

Last updated 2026-08-06 21:46:43

Assigner GitHub_M

CVSS score not scored

State PUBLISHED

Description

h2 is a pure-Python implementation of a HTTP/2 protocol stack. Versions up to and including 4.4.0 accept request header blocks containing more than one Host header, and forward every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, providing a request smuggling primitive. This issue is fixed in version 4.4.1.

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