The php_handler function in sapi/apache2handler/sapi_apache2.c in PHP before 5.4.40, 5.5.x before 5.5.24, and 5.6.x before 5.6.8, when the Apache HTTP Server 2.4.x is used, allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via pipelined HTTP requests that result in a "deconfigured interpreter."