Double free vulnerability in the php_wddx_process_data function in wddx.c in the WDDX extension in PHP before 5.5.37, 5.6.x before 5.6.23, and 7.x before 7.0.8 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via crafted XML data that is mishandled in a wddx_deserialize call.