fastify fast-uri up to 2.4.7/3.1.8/4.2.2 Host Canonicalization canonicalizeHost input validation

Summaryinfo

A vulnerability identified as critical has been detected in fastify fast-uri up to 2.4.7/3.1.8/4.2.2. This affects the function canonicalizeHost of the component Host Canonicalization. This manipulation causes input validation. This vulnerability appears as CVE-2026-110180. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in fastify fast-uri up to 2.4.7/3.1.8/4.2.2. It has been declared as critical. Affected by this vulnerability is the function canonicalizeHost of the component Host Canonicalization. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

fast-uri is a dependency-free RFC 3986 URI parser and serializer for Node.js. In versions from 2.4.2 through 2.4.7, from 3.1.3 through 3.1.8, and from 4.0.1 through 4.2.2, for HTTP-family schemes the canonicalizeHost() function passes the parsed host to the WHATWG URL parser and adopts its hostname without checking that the parser consumed the entire input as a host, so the authority can be silently rewritten: data before an at-sign is dropped and tab, carriage-return, and line-feed characters are stripped, with no error reported. An application that enforces host-based policy such as denylists, loopback filtering, redirect validation, or outbound proxy routing on one representation can then see the canonical host diverge from what it checked, allowing traffic to be steered to an unintended destination. The issue is fixed in fast-uri 2.4.8, 3.1.9, and 4.2.3, and users should upgrade to one of these versions or later. As a workaround, reject an authority that contains more than one at-sign or any tab, carriage-return, or line-feed before calling fast-uri, or treat any non-empty parse error as fatal and compare hosts only from the same parse result.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-110180 since 10/13/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 367762 (Linux Distros Unpatched Vulnerability : CVE-2026-110180), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.4.8, 3.1.9 or 4.2.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (367762) and EUVD (EUVD-2026-104813). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• fastify

Name

• fast-uri

Version

• 2.4.0
• 2.4.1
• 2.4.2
• 2.4.3
• 2.4.4
• 2.4.5
• 2.4.6
• 2.4.7
• 3.1.0
• 3.1.1
• 3.1.2
• 3.1.3
• 3.1.4
• 3.1.5
• 3.1.6
• 3.1.7
• 3.1.8
• 4.2.0
• 4.2.1
• 4.2.2

Website

• Product: https://github.com/fastify/fast-uri/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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