The i_zval_ptr_dtor function in Zend/zend_variables.h in PHP 7.1.5 allows attackers to cause a denial of service (memory consumption and application crash) or possibly have unspecified other impact by triggering crafted operations on array data structures.
Created php tracking bugs for this issue:
Affects: fedora-all [bug 1456751]
This seems to be more like a memory exhaustion which is caused by malicious PHP script. I dont see this as being triggerable by a malicious PHP application user.