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CVE-2026-25896
CRITICAL9.3
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.
CVE Details
CVSS v3.1 Score9.3
SeverityCRITICAL
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
Attack VectorNETWORK
ComplexityLOW
Privileges RequiredNONE
User InteractionNONE
Published2/20/2026
Last Modified3/2/2026
Sourcenvd
Honeypot Sightings0
Affected Products
naturalintelligence:fast-xml-parser
Weaknesses (CWE)
CWE-185
References
https://github.com/NaturalIntelligence/fast-xml-parser/commit/943ef0eb1b2d3284e72dd74f44a042ee9f07026e(security-advisories@github.com)
https://github.com/NaturalIntelligence/fast-xml-parser/commit/ddcd0acf26ddd682cb0dc15a2bd6aa3b96bb1e69(security-advisories@github.com)
https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.5(security-advisories@github.com)
https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-m7jm-9gc2-mpf2(security-advisories@github.com)
IOC Correlations
No correlations recorded
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