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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. From 4.1.3to before 5.3.5, a dot (.) in a DOCTYPE entity name is treated as a regex wildcard during entity replacement, allowing an attacker to shadow built-in XML entities (<, >, &, ", ') with arbitrary values. This bypasses entity encoding and leads to XSS when parsed output is rendered. This vulnerability is fixed in 5.3.5.

PUBLISHED Reserved 2026-02-06 | Published 2026-02-20 | Updated 2026-02-23 | Assigner GitHub_M




CRITICAL: 9.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N

Problem types

CWE-185: Incorrect Regular Expression

Product status

>= 4.1.3, < 5.3.5
affected

References

github.com/...parser/security/advisories/GHSA-m7jm-9gc2-mpf2

github.com/...ommit/943ef0eb1b2d3284e72dd74f44a042ee9f07026e

github.com/...ommit/ddcd0acf26ddd682cb0dc15a2bd6aa3b96bb1e69

github.com/...telligence/fast-xml-parser/releases/tag/v5.3.5

cve.org (CVE-2026-25896)

nvd.nist.gov (CVE-2026-25896)

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