This page tracks the Debian fix status. The vulnerability itself is described on the main CVE page.
View CVE-2026-71554 →
DEBIAN-CVE-2026-71554
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 on...
Original description
The description as published by the source.
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.
Source: OSV.dev (Open Source Vulnerabilities) OSV
Affected packages
Debian:12
python-h2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Debian:13
python-h2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Debian:14
python-h2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
References
- advisory security-tracker.debian.org