CVE-2026-25896 (GCVE-0-2026-25896)

Vulnerability from cvelistv5 – Published: 2026-02-20 20:57 – Updated: 2026-03-02 19:11
VLAI?
Title
fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names
Summary
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.
Severity ?
9.3 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
CWE
  • CWE-185 - Incorrect Regular Expression
Assigner
References
Impacted products
Vendor Product Version
NaturalIntelligence fast-xml-parser Affected: >= 5.0.0, < 5.3.5
Affected: >= 4.1.3, < 4.5.4
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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