fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv. In versions before 2.4.7, from 3.0.0 through 3.1.7, and from 4.0.0 through 4.1.4, fast-uri folds the host to lowercase before it percent-decodes the host, so a percent-encoded uppercase octet such as %41 decodes to a literal A that is never folded. For a scheme-relative reference such as //host there is no scheme, so the host canonicalization that would normally repair this does not run, and parse, normalize, and equal then disagree on the same host. An application that makes a case-sensitive host decision on fast-uri output, for example a host allowlist or denylist that compares the parsed host or uses equal, can be steered past the check with a percent-encoded uppercase octet, and because hostnames are case-insensitive in DNS and HTTP the evading spelling still reaches the host the check meant to gate. The issue is fixed in fast-uri 2.4.7, 3.1.8, and 4.1.5, and users should upgrade to one of those versions or later. As a workaround, compare hosts case-insensitively by lowercasing the parsed host before any allowlist or denylist decision.

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

  - fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv. In versions before
    2.4.7, from 3.0.0 through 3.1.7, and from 4.0.0 through 4.1.4, fast-uri folds the host to lowercase before
    it percent-decodes the host, so a percent-encoded uppercase octet such as %41 decodes to a literal A that
    is never folded. For a scheme-relative reference such as //host there is no scheme, so the host
    canonicalization that would normally repair this does not run, and parse, normalize, and equal then
    disagree on the same host. An application that makes a case-sensitive host decision on fast-uri output,
    for example a host allowlist or denylist that compares the parsed host or uses equal, can be steered past
    the check with a percent-encoded uppercase octet, and because hostnames are case-insensitive in DNS and
    HTTP the evading spelling still reaches the host the check meant to gate. The issue is fixed in fast-uri
    2.4.7, 3.1.8, and 4.1.5, and users should upgrade to one of those versions or later. As a workaround,
    compare hosts case-insensitively by lowercasing the parsed host before any allowlist or denylist decision.
    (CVE-2026-86472)

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

  - fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv. In versions before     2.4.7, from 3.0.0 through 3.1.7, and from 4.0.0 through 4.1.4, fast-uri folds the host to lowercase before     it percent-decodes the host, so a percent-encoded uppercase octet such as %41 decodes to a literal A that     is never folded. For a scheme-relative reference such as //host there is no scheme, so the host     canonicalization that would normally repair this does not run, and parse, normalize, and equal then     disagree on the same host. An application that makes a case-sensitive host decision on fast-uri output,     for example a host allowlist or denylist that compares the parsed host or uses equal, can be steered past     the check with a percent-encoded uppercase octet, and because hostnames are case-insensitive in DNS and     HTTP the evading spelling still reaches the host the check meant to gate. The issue is fixed in fast-uri     2.4.7, 3.1.8, and 4.1.5, and users should upgrade to one of those versions or later. As a workaround,     compare hosts case-insensitively by lowercasing the parsed host before any allowlist or denylist decision.
    (CVE-2026-86472)

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

ID	Name	Product	Family	Type	Severity
460539	Echo: fast-uri: security update to 2.4.7	Tenable Cloud Security	Echo Local Security Checks	Local	medium
460539	Echo: fast-uri: security update to 2.4.7	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	medium
345880	Linux Distros Unpatched Vulnerability : CVE-2026-86472	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-86472

medium

Tenable Plugins

medium

medium

medium