CVE-2026-27942

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. Prior to version 5.3.8, the application crashes with stack overflow when user use XML builder with `preserveOrder:true`. Version 5.3.8 fixes the issue. As a workaround, use XML builder with `preserveOrder:false` or check the input data before passing to builder.

• https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a
• https://github.com/NaturalIntelligence/fast-xml-parser/pull/791
• https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3