Description
fast-uri serializes the port component of a URI without validating it. When recomposing the authority, the userinfo and host components are escaped but the port is concatenated verbatim, so a port value that is not a sequence of digits can inject authority delimiters, demoting the intended host to userinfo and pointing the authority at an attacker-controlled host. Both fast-uri and Node's URL read the result back as the attacker's host with no error, so re-validating the built URI does not catch it. This affects applications that build URIs from parts and assign untrusted data to the port component through the serialize, normalize, or equal functions in their object forms. The issue affects fast-uri versions before 2.4.6, from 3.0.0 before 3.1.7, and from 4.0.0 before 4.1.4. It is fixed in 2.4.6, 3.1.7, and 4.1.4, where recomposeAuthority rejects any port that is not a digit sequence per RFC 3986.
Published: 2026-09-02
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

No vendor fix or workaround currently provided.

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History

Wed, 02 Sep 2026 20:15:00 +0000

Type Values Removed Values Added
Description fast-uri serializes the port component of a URI without validating it. When recomposing the authority, the userinfo and host components are escaped but the port is concatenated verbatim, so a port value that is not a sequence of digits can inject authority delimiters, demoting the intended host to userinfo and pointing the authority at an attacker-controlled host. Both fast-uri and Node's URL read the result back as the attacker's host with no error, so re-validating the built URI does not catch it. This affects applications that build URIs from parts and assign untrusted data to the port component through the serialize, normalize, or equal functions in their object forms. The issue affects fast-uri versions before 2.4.6, from 3.0.0 before 3.1.7, and from 4.0.0 before 4.1.4. It is fixed in 2.4.6, 3.1.7, and 4.1.4, where recomposeAuthority rejects any port that is not a digit sequence per RFC 3986.
Title fast-uri vulnerable to authority injection via an unvalidated port in serialize
Weaknesses CWE-116
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'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-09-02T20:09:51.415Z

Reserved: 2026-09-01T16:10:49.688Z

Link: CVE-2026-84292

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-02T20:17:39.543

Modified: 2026-09-02T20:17:39.543

Link: CVE-2026-84292

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-116

    Improper Encoding or Escaping of Output