CVEvulnerability

CVE-2026-71554

5.3 MEDIUM Published 2026-08-06 Modified 2026-10-24 Official page ↗
Status
Deferred
Published
2026-08-06
Last modified
2026-10-24
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weaknesses
CWE-444

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.

Related

Weakness · CWE (1)

  • CWE-444 Inconsistent Interpretation of HTTP Requests weakness

References