CVE-2026-75931 (GCVE-0-2026-75931)

Vulnerability from cvelistv5 – Published: 2026-08-24 09:30 – Updated: 2026-08-24 16:28
VLAI
Title
fast-uri vulnerable to host confusion via skipped IDN canonicalization on scheme-relative references
Summary
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-24 16:28 UTC
CWE
  • CWE-436 - Interpretation Conflict
Assigner
openjs CNA under the redhat root
CNA scorecard C 65/100 over 118 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
fast-uri fast-uri Affected: 2.4.2 , < 2.4.5 (semver)
Unaffected: 2.4.5 (semver)
Affected: 3.1.3 , < 3.1.6 (semver)
Unaffected: 3.1.6 (semver)
Affected: 4.0.1 , < 4.1.3 (semver)
Unaffected: 4.1.3 (semver)
guessed Create a notification for this product.
Credits
baeseungwon1010 mcollina UlisesGascon
Show details on NVD website
To clipboard 

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