CVE-2026-110725
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URI Parsing Issue in fast-uri Leading to XSS

Vulnerability report for CVE-2026-110725, 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, when serialize(), normalize(), or resolve() are called with the non-default option reference set to suffix on a reference that has no authority, the emitted relative reference can contain a bare colon in its first path segment without escaping it, even though RFC 3986 forbids that because it makes the string reparse as an absolute URI with a scheme. An application that serializes or normalizes a relative reference with the suffix option and then treats the result as a URI can turn inert input into a live javascript, data, or vbscript URL, a cross-site scripting vector, and the equal() comparison can conflate a scheme-bearing reference with a relative one. Exposure is limited to applications using the non-default suffix reference option. 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, avoid the suffix reference option on untrusted input, or percent-encode a colon in the first path segment of the result before treating it as a URI.

CVSS Scores

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Meta Information

Published
2026-10-20
Last Modified
2026-10-20
Generated
2026-11-09
AI Q&A
2026-10-20
EPSS Evaluated
2026-11-08
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
KEV Icon
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.
CWE-116 The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.

Attack-Flow Graph

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Executive Summary

This vulnerability affects the fast-uri library in Node.js. When using non-default 'suffix' reference option, functions like serialize(), normalize(), or resolve() fail to properly escape a colon in the first path segment of a relative URI without authority. This can cause the URI to be misinterpreted as an absolute URI with a scheme (e.g., javascript:, data:), potentially enabling cross-site scripting if the output is treated as a URI.

Detection Guidance

To detect this vulnerability, check if your application uses fast-uri versions before 2.4.8, 3.1.9, or 4.2.3. Inspect code for use of the suffix reference option in serialize(), normalize(), or resolve() functions. Look for untrusted input being processed with these functions.

Impact Analysis

If your application uses fast-uri with the 'suffix' option on untrusted input, an attacker could craft malicious URIs that bypass security checks. When processed, these URIs may execute unintended scripts (e.g., JavaScript) if treated as absolute URIs, leading to cross-site scripting attacks. The impact is limited to applications using the 'suffix' option.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR or HIPAA as it is a low-severity issue in URI parsing that could enable cross-site scripting if misused. However, if exploited, it might lead to unauthorized data access or script execution, potentially violating GDPR's integrity principle or HIPAA's security requirements for protected health information.

Mitigation Strategies

Upgrade fast-uri to version 2.4.8, 3.1.9, or 4.2.3 or later. If upgrading is not possible, avoid using the suffix reference option on untrusted input or percent-encode colons in the first path segment before URI processing.

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