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Vulnerability record · CVE-2026-25128 · published 30 January 2026

CVE-2026-25128: Naturalintelligence fast-xml-parser improper input validation vulnerability

Naturalintelligence · Fast Xml Parser

fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 5.0.9 through 5.3.3, a RangeError vulnerability exists in the numeric entity processing of fast-xml-parser when parsing XML with out-of-range entity code points (e.g., `�` or `�`). This causes the parser to throw an uncaught exception, crashing any application that processes untrusted XML input. Version 5.3.4 fixes the issue.

7.5 CVSS 3.1 High EPSS 0.58% · top 54.5% CWE-20 · Improper input validationCWE-248 · CWE-248
7.5CVSS 3.1 base score
0.58%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 1 tagged exploit
17 Jun 2026Last modified by NVD

Description

fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 5.0.9 through 5.3.3, a RangeError vulnerability exists in the numeric entity processing of fast-xml-parser when parsing XML with out-of-range entity code points (e.g., `�` or `�`). This causes the parser to throw an uncaught exception, crashing any application that processes untrusted XML input. Version 5.3.4 fixes the issue.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/NaturalIntelligence/fast-xml-parser/commit/4e387f61c4a5cef792f6a2f42467013290bf95dc Patch
https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.4 Release Notes
https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-37qj-frw5-hhjh ExploitVendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-25128), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.