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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. 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.

PUBLISHED Reserved 2026-02-12 | Published 2026-02-19 | Updated 2026-02-19 | Assigner GitHub_M




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-776: Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

Product status

>= 4.1.3, < 5.3.6
affected

References

github.com/...parser/security/advisories/GHSA-jmr7-xgp7-cmfj

github.com/...ommit/910dae5be2de2955e968558fadf6e8f74f117a77

github.com/...telligence/fast-xml-parser/releases/tag/v5.3.6

cve.org (CVE-2026-26278)

nvd.nist.gov (CVE-2026-26278)

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