CVE-2026-27942: fast-xml-parser has stack overflow in XMLBuilder with preserveOrder

Application crashes with stack overflow when user use XML builder with prserveOrder:true for following or similar input

[{
'foo': [
{ 'bar': [{ '@_V': 'baz' }] }
]
}]

Cause: arrToStr was not validating if the input is an array or a string and treating all non-array values as text content. What kind of vulnerability is it? Who is impacted?