fast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-family URLs. The IDN conversion path calls a helper that does not exist on the global URL constructor, silently leaving the host in its original Unicode form while normalize() and equal() still return values that differ from a WHATWG-compatible URL parser. Applications that use fast-uri to enforce host-based policy (denylists, loopback filtering, redirect validation, outbound proxy routing) before passing the same URL to Node's URL or fetch can be bypassed when the two implementations resolve the same input to different hosts. Patches: upgrade to fast-uri 3.1.3 for the 3.x line or 4.0.1 for the 4.x line. Workarounds: enforce host policy using the same URL parser used for the actual request, or reject non-ASCII hosts before policy checks.

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

  - fast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-
    family URLs. The IDN conversion path calls a helper that does not exist on the global URL constructor,
    silently leaving the host in its original Unicode form while normalize() and equal() still return values
    that differ from a WHATWG-compatible URL parser. Applications that use fast-uri to enforce host-based
    policy (denylists, loopback filtering, redirect validation, outbound proxy routing) before passing the
    same URL to Node's URL or fetch can be bypassed when the two implementations resolve the same input to
    different hosts. Patches: upgrade to fast-uri 3.1.3 for the 3.x line or 4.0.1 for the 4.x line.
    Workarounds: enforce host policy using the same URL parser used for the actual request, or reject non-
    ASCII hosts before policy checks. (CVE-2026-13676)

The remote openSUSE 16 host has a package installed that is affected by a vulnerability as referenced in the openSUSE- SU-2026:21231-1 advisory.

    Changes in python-pydata-sphinx-theme:

    - CVE-2026-13676: fast-uri: failure to canonicalize Unicode/IDN       hostnames for HTTP-family URLs allows for bypass (bsc#1269597)
      * revendor the vendored tarball with updated versions

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.

  - fast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-     family URLs. The IDN conversion path calls a helper that does not exist on the global URL constructor,     silently leaving the host in its original Unicode form while normalize() and equal() still return values     that differ from a WHATWG-compatible URL parser. Applications that use fast-uri to enforce host-based     policy (denylists, loopback filtering, redirect validation, outbound proxy routing) before passing the     same URL to Node's URL or fetch can be bypassed when the two implementations resolve the same input to     different hosts. Patches: upgrade to fast-uri 3.1.3 for the 3.x line or 4.0.1 for the 4.x line.
    Workarounds: enforce host policy using the same URL parser used for the actual request, or reject non-     ASCII hosts before policy checks. (CVE-2026-13676)

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

ID	Name	Product	Family	Severity
445121	SCA: security update for fast-uri (GHSA-4c8g-83qw-93j6)	Tenable Cloud Security	SCA Checks	high
445121	SCA: security update for fast-uri (GHSA-4c8g-83qw-93j6)	Tenable Self-Hosted Container Security	SCA Checks	high
325130	openSUSE 16 Security Update : python-pydata-sphinx-theme (openSUSE-SU-2026:21231-1)	Nessus	SuSE Local Security Checks	high
323932	Linux Distros Unpatched Vulnerability : CVE-2026-13676	Nessus	Misc.	high

Detections

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CVE-2026-13676

high

Tenable Plugins

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high

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