The SoapClient __call method in ext/soap/soap.c in PHP before 5.4.45, 5.5.x before 5.5.29, and 5.6.x before 5.6.13 does not properly manage headers, which allows remote attackers to execute arbitrary code via crafted serialized data that triggers a type confusion in the serialize_function_call function.<a href=http://cwe.mitre.org/data/definitions/843.html>CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')</a> http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6836