CVE-2026-26278
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. In versions 4.1.3 through 5.3.5, the XML parser can be forced to do an unlimited amount of entity expansion. With a very small XML input, it’s possible to make the parser spend seconds or even minutes processing a single request, effectively freezing the application. Version 5.3.6 fixes the issue. As a workaround, avoid using DOCTYPE parsing by `processEntities: false` option.
Scoring
- Severity
- HIGH
- CVSS base score
- 7.5
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS probability
- 0.84%
- CWE
- CWE-776
- Published
- 2026-02-19
- Last modified
- 2026-09-10
Affected products
- NaturalIntelligence fast-xml-parser
- NaturalIntelligence fast-xml-parser
Weakness type
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