CVE-2026-110095
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Path Traversal in fast-uri Library

Vulnerability report for CVE-2026-110095, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-10-20

Last updated on: 2026-10-20

Assigner: openjs

Description

fast-uri is a dependency-free RFC 3986 URI parser and serializer for Node.js. In versions before 2.4.8, from 3.0.0 through 3.1.8, and from 4.0.0 through 4.2.2, the normalize() and serialize() functions apply RFC 3986 dot-segment removal to the path of a relative-path reference, even though that algorithm is defined only for the merged target path during resolution, so a leading parent-directory segment can be dropped and a document-relative reference can become root-relative. An application that normalizes an attacker-supplied or user-supplied relative reference and then resolves it, or uses it as a cache, deduplication, or authorization key, can have the reference escape its intended directory and point at a different resource. The issue is fixed in fast-uri 2.4.8, 3.1.9, and 4.2.3, and users should upgrade to one of these versions or later. As a workaround, resolve a relative reference against its absolute base first and normalize the absolute result instead of normalizing the reference beforehand.

CVSS Scores

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Meta Information

Published
2026-10-20
Last Modified
2026-10-20
Generated
2026-11-10
AI Q&A
2026-10-20
EPSS Evaluated
2026-11-09
NVD
EUVD

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
fast-uri fast-uri 0
fast-uri fast-uri 3.0.0
fast-uri fast-uri 4.0.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-41 The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.

Attack-Flow Graph

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Executive Summary

This vulnerability affects the fast-uri library in Node.js. It involves incorrect handling of relative paths during normalization. The normalize() and serialize() functions improperly apply RFC 3986's dot-segment removal to relative paths, causing leading parent-directory segments (..) to be dropped. This can convert document-relative references into root-relative ones, leading to unintended resource access.

Detection Guidance

Check the version of fast-uri in your Node.js project using 'npm list fast-uri' or 'yarn list fast-uri'. If the version is before 2.4.8, 3.1.9, or 4.2.3, the system is vulnerable.

Impact Analysis

An attacker could exploit this to manipulate paths in applications using vulnerable fast-uri versions. This may cause cache, deduplication, or authorization mechanisms to fail, leading to unauthorized access to files or resources outside intended directories. The impact is limited but could enable disclosure of file system contents through path equivalence manipulations.

Compliance Impact

This vulnerability could potentially affect compliance with GDPR and HIPAA by enabling unauthorized access to files or resources outside intended directories. If an application normalizes attacker-supplied relative paths before resolution, it may inadvertently grant access to sensitive data, violating data protection requirements under these regulations.

Mitigation Strategies

Upgrade fast-uri to version 2.4.8, 3.1.9, or 4.2.3 or later. If immediate upgrade is not possible, resolve relative references against their absolute base before normalizing them as a workaround.

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