libical 4.0.6 contains an incompatible function pointer in icalparameter_string_to_kind(). When parsing iCalendar data containing a parameterized property, the function passes icalparameter_compare_kind_map() to bsearch() through an incompatible comparator function pointer type. bsearch() invokes the callback through the mismatched type, resulting in undefined behavior and process termination, leading to denial of service.
https://github.com/libical/libical/pull/1363/changes/557d9c043733b33a8511dce41fdeeb508460d5a9