The SoapClient::__call method in ext/soap/soap.c in PHP before 5.4.39, 5.5.x before 5.5.23, and 5.6.x before 5.6.7 does not verify that __default_headers is an array, which allows remote attackers to execute arbitrary code by providing crafted serialized data with an unexpected data type, related to a "type confusion" issue.
Exploitability
AV:NAC:LAu:NImpact
C:PI:PA:P7.5/AV:N/AC:L/Au:N/C:P/I:P/A:P