The phpwddxpushelement function in ext/wddx/wddx.c in PHP before 5.6.26 and 7.x before 7.0.11 allows remote attackers to cause a denial of service (invalid pointer access and out-of-bounds read) or possibly have unspecified other impact via an incorrect boolean element in a wddxPacket XML document, leading to mishandling in a wddxdeserialize call.