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Critical · 9.3 CVE-2026-25896 EUVD-2026-7529GHSA-m7jm-9gc2-mpf2

fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names

Published Feb 20, 2026 · Updated Sep 10, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
NaturalIntelligence fast-xml-parser >= 5.0.0, < 5.3.5, >= 4.1.3, < 4.5.4 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 node-webfont No fix yet —
Debian 13 node-webfont No fix yet —
Debian 12 node-webfont No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 node-webfont No fix yet —
Ubuntu 26.04 LTS node-webfont No fix yet —
Ubuntu 25.10 node-webfont No fix yet —
Ubuntu 24.04 LTS node-webfont No fix yet —

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling prism 5.14.3-r7 —
Wolfi rolling renovate 43.48.3-r0 —
Wolfi rolling saf 1.6.0-r0 —
Wolfi rolling tileserver-gl 5.5.0-r5 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm fast-xml-parser >= 5.0.0, < 5.3.5 5.3.5 GHSA-m7jm-9gc2-mpf2
npm fast-xml-parser >= 4.1.3, < 4.5.4 4.5.4 GHSA-m7jm-9gc2-mpf2

Advisories 2

References