fast-xml-parser regex vulnerability patch could be improved from a safety perspective
Summary
This is a comment on https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-6w63-h3fj-q4vw and the patches fixing it.
Details
The code which validates a name calls the validator: https://github.com/NaturalIntelligence/fast-xml-parser/blob/ecf6016f9b48aec1a921e673158be0773d07283e/src/xmlparser/DocTypeReader.js#L145-L153 This checks for the presence of an invalid character. Such an approach is always risky, as it is so easy to forget to include an invalid character in the list. A safer approach is to validate entity names against the XML specification: https://www.w3.org/TR/xml11/#sec-common-syn - an ENTITY name is a Name:
[4] NameStartChar ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] |
[#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] |
[#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]
[4a] NameChar ::= NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]
[5] Name ::= NameStartChar (NameChar)*so the safest way to validate an entity name is to build a regex to represent this expression and check whether the name given matches the regex. (Something along the lines of /^[name start char class][name char class]*$/.) There's probably a nice way to simplify the explicit list rather than typing it out verbatim using Unicode character properties, but I don't know enough to do so.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de npm | fast-xml-parser | >= 4.2.4, < 4.2.5 | 4.2.5 |
Referencias
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-6w63-h3fj-q4vw
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-gpv5-7x3g-ghjv
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/9a880b887916855c3a510869fd1ee268d7fe58b1
- https://github.com/NaturalIntelligence/fast-xml-parser
- Debilidad (CWE)
-- Plataforma
- npm
- Paquete
fast-xml-parser- Publicada
- 15.06.2023
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-gpv5-7x3g-ghjv - CC BY 4.0
Historial de vulnerabilidades: fast-xml-parser
Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 12
- Primera → última
- 08.2021 07.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 1
- Alta 6
- Media 3
- Baja 2
Divulgaciones por año
- 2021: 1
- 2022: 0
- 2023: 2
- 2024: 1
- 2025: 0
- 2026: 8
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fast-xml-parser regex vulnerability patch could be improved from a safety perspective esta entrada
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