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.
Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-6hr6-w5qg-qmwg | h2: Duplicate Host header could facilitate request smuggling |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 08 Aug 2026 03:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Fri, 07 Aug 2026 10:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Python-hyper
Python-hyper h2 |
|
| Vendors & Products |
Python-hyper
Python-hyper h2 |
Thu, 06 Aug 2026 22:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | h2: Duplicate Host header could facilitate request smuggling | |
| Weaknesses | CWE-444 | |
| References |
| |
| Metrics |
cvssV3_1
|
Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-08-08T02:49:30.505Z
Reserved: 2026-08-06T21:24:15.376Z
Link: CVE-2026-71554
Updated: 2026-08-08T02:49:26.583Z
No data.
No data.
OpenCVE Enrichment
Updated: 2026-08-07T09:58:41Z
Weaknesses
Github GHSA