The php_wddx_pop_element function in ext/wddx/wddx.c in PHP before 5.6.25 and 7.x before 7.0.10 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) or possibly have unspecified other impact via an invalid base64 binary value, as demonstrated by a wddx_deserialize call that mishandles a binary element in a wddxPacket XML document.