fast-uri accepts a host that contains an unbalanced or misplaced authority bracket without reporting an error. A host that starts with an opening bracket but does not end with a closing bracket is neither validated as an IP literal nor canonicalized as a domain name, so parse() returns it as the host with error undefined, while Node's URL and the HTTP clients built on it resolve the same string to a different host. An application that reads the parsed host to make a host decision, such as an SSRF denylist, a redirect allowlist, or proxy routing, and then passes the original URL to an HTTP client evaluates its policy against a string that is not the host the request reaches. The same host is carried through normalize, equal, and resolve. This affects fast-uri versions 2.4.5, 3.1.6, and 4.1.3, and is fixed in 2.4.6, 3.1.7, and 4.1.4, where parse() reports a malformed host for any host that contains a bracket but is not a valid IPv6 literal.

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History

Thu, 03 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 03 Sep 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1289
References
Metrics threat_severity

None

threat_severity

Important


Thu, 03 Sep 2026 10:00:00 +0000

Type Values Removed Values Added
First Time appeared Fast-uri
Fast-uri fast-uri
Vendors & Products Fast-uri
Fast-uri fast-uri

Wed, 02 Sep 2026 20:30:00 +0000

Type Values Removed Values Added
Description fast-uri accepts a host that contains an unbalanced or misplaced authority bracket without reporting an error. A host that starts with an opening bracket but does not end with a closing bracket is neither validated as an IP literal nor canonicalized as a domain name, so parse() returns it as the host with error undefined, while Node's URL and the HTTP clients built on it resolve the same string to a different host. An application that reads the parsed host to make a host decision, such as an SSRF denylist, a redirect allowlist, or proxy routing, and then passes the original URL to an HTTP client evaluates its policy against a string that is not the host the request reaches. The same host is carried through normalize, equal, and resolve. This affects fast-uri versions 2.4.5, 3.1.6, and 4.1.3, and is fixed in 2.4.6, 3.1.7, and 4.1.4, where parse() reports a malformed host for any host that contains a bracket but is not a valid IPv6 literal.
Title fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority
Weaknesses CWE-436
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-09-03T13:14:42.123Z

Reserved: 2026-09-01T16:42:27.072Z

Link: CVE-2026-84394

cve-icon Vulnrichment

Updated: 2026-09-03T13:14:39.311Z

cve-icon NVD

Status : Received

Published: 2026-09-03T05:16:38.680

Modified: 2026-09-03T14:17:03.060

Link: CVE-2026-84394

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-02T20:25:35Z

Links: CVE-2026-84394 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-03T13:45:04Z

Weaknesses