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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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.
    (CVE-2026-71554)

The remote openSUSE 16 host has a package installed that is affected by a vulnerability as referenced in the openSUSE- SU-2026:21693-1 advisory.

    This update for python-h2 fixes the following issue:

    - CVE-2026-71554: duplicate `Host` headers are accepted and forwarded to consuming applications, which can     lead to       request smuggling (bsc#1274386).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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.
    (CVE-2026-71554)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
458084	Echo: h2: security update to 4.4.1	Tenable Cloud Security	Echo Local Security Checks	Local	medium
458084	Echo: h2: security update to 4.4.1	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	medium
342114	openSUSE 16 Security Update : python-h2 (openSUSE-SU-2026:21693-1)	Nessus	SuSE Local Security Checks	Local	medium
445758	SCA: security update for h2 (GHSA-6hr6-w5qg-qmwg)	Tenable Cloud Security	SCA Checks	Local	medium
445758	SCA: security update for h2 (GHSA-6hr6-w5qg-qmwg)	Tenable Self-Hosted Container Security	SCA Checks	Local	medium
333322	Linux Distros Unpatched Vulnerability : CVE-2026-71554	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-71554

medium

Tenable Plugins

medium

medium

medium

medium

medium

medium