Description
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.
Published: 2026-10-20
Score: 4.8 Medium
EPSS: < 1% Very Low
KEV: No
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History

Tue, 20 Oct 2026 12:45:00 +0000

Type Values Removed Values Added
Description 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.
Title fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization
Weaknesses CWE-1286
CWE-20
CWE-436
References
Metrics threat_severity

None

 cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'}

threat_severity

Moderate

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-10-20T07:00:42.153Z

Reserved: 2026-10-13T17:13:53.507Z

Link: CVE-2026-110180

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-20T07:17:08.687

Modified: 2026-10-20T07:17:08.687

Link: CVE-2026-110180

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-20T07:00:42Z

Links: CVE-2026-110180 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-1286

    Improper Validation of Syntactic Correctness of Input

  • CWE-20

    Improper Input Validation

  • CWE-436

    Interpretation Conflict