Vulnerability 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.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Naturalintelligence | Fast-Xml-Parser | >= 4.1.3, < 5.3.5 |
Related Weaknesses (CWE)
References
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/943ef0eb1b2d3284e7Patch
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/ddcd0acf26ddd682cbPatch
- https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.5ProductRelease Notes
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-ExploitMitigationVendor Advisory
FAQ
What is CVE-2026-25896?
CVE-2026-25896 is a vulnerability with a CVSS score of 9.3 (CRITICAL). 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 entit...
How severe is CVE-2026-25896?
CVE-2026-25896 has been rated CRITICAL with a CVSS base score of 9.3/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-25896?
Check the references section above for vendor advisories and patch information. Affected products include: Naturalintelligence Fast-Xml-Parser.