REDHAT-BUG-2521777: High severity npm/fast-uri vulnerability

Published Aug 24, 2026
·
Updated

fast-uri is a URI parser for Node.js. It canonicalizes a host to its ASCII form only when the input carries an explicit scheme, so a scheme-relative reference such as a host preceded by two slashes is returned with its host verbatim and no error set. As a result fast-uri's own entry points disagree with each other: parse, resolve, normalize, and equal can yield different hosts for the same input depending only on whether a scheme is written out, and equal can return opposite verdicts for the same pair of hosts. An application that extracts a host with fast-uri to check it against a policy list and then resolves the same reference can make its decision on one host while the destination is another, enabling host confusion and policy bypass. The affected versions are 2.4.2 up to but not including 2.4.5, 3.1.3 up to but not including 3.1.6, and 4.0.1 up to but not including 4.1.3. The issue is fixed in 2.4.5, 3.1.6, and 4.1.3, which canonicalize the host consistently across the resolve path. Users should upgrade to a patched version.

Affected Software

1 affected component
npm/fast-uri>=2.4.2<2.4.5, >=3.1.3<3.1.6, >=4.0.1<4.1.3

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade fast-uri to a version that resolves this vulnerability.

    Fixed in 2.4.5
  2. Upgrade

    Upgrade fast-uri to a version that resolves this vulnerability.

    Fixed in 3.1.6
  3. Upgrade

    Upgrade fast-uri to a version that resolves this vulnerability.

    Fixed in 4.1.3

Event History

Aug 24, 2026
Data Sourced
via Red Hat·09:51 AM
DescriptionSeverityAffected Software

Contact

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