Cpanel::JSON::XS versions from 3.0202 before 4.80 for Perl leak memory and retain overloaded objects when encoding values as strings in encode stringify.

encode stringify writes a value in its string form under allow stringify, under convert blessed for objects without TO JSON, and under allow bignum. For an array or hash object with a "" overload, and from 4.20 a scalar object, it takes an extra reference that is never released, so the object and everything it references are never freed. From 4.10 it also never frees its copy of the string.

Repeatedly encoding data that contains such values grows process memory without bound.