CVE-2026-84394

fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority

Published Sep 2, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-58mr-gqgx-xq4g fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority
History
Type Values Removed Values Added
First Time appeared Openjsf
Openjsf fast-uri
CPEs cpe:2.3:a:openjsf:fast-uri:2.4.5:*:*:*:*:node.js:*:*
cpe:2.3:a:openjsf:fast-uri:3.1.6:*:*:*:*:node.js:*:*
cpe:2.3:a:openjsf:fast-uri:4.1.3:*:*:*:*:node.js:*:*
Vendors & Products Openjsf
Openjsf fast-uri
Type Values Removed Values Added
Metrics ssvc

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
openjs
Published
Updated
Sep 3, 2026, 1:14 PM
Reserved
Sep 1, 2026, 4:42 PM
Status
Analyzed
Published
Sep 3, 2026, 5:16 AM
Modified
Sep 4, 2026, 4:12 PM
Severity
Important
Public date
Sep 2, 2026, 8:25 PM