nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.

The remote openSUSE 16 host has packages installed that are affected by a vulnerability as referenced in the openSUSE- SU-2026:21302-1 advisory.

    This update for nghttp2 fixes the following issue

    - CVE-2026-58055: HTTP request/response smuggling via upgrade request with `Content-Length` (bsc#1269489).

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 remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by a vulnerability as referenced in the USN-8495-1 advisory.

    It was discovered that the nghttp2 nghttpx proxy incorrectly handled HTTP/1.1 Upgrade requests that     included a Content-Length header and body. A remote attacker could possibly use this issue to perform HTTP     request and response smuggling attacks against backend services.

Tenable has extracted the preceding description block directly from the Ubuntu 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.

  - nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-     Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection     headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in     the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.
    (CVE-2026-58055)

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

ID	Name	Product	Family	Severity
326667	openSUSE 16 Security Update : nghttp2 (openSUSE-SU-2026:21302-1)	Nessus	SuSE Local Security Checks	medium
325013	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : nghttp2 vulnerability (USN-8495-1)	Nessus	Ubuntu Local Security Checks	medium
323595	Linux Distros Unpatched Vulnerability : CVE-2026-58055	Nessus	Misc.	medium

Detections

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CVE-2026-58055

medium

Tenable Plugins

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medium

medium