PHP 4.4.2 and 5.1.2 allows local users to cause a crash (segmentation fault) by defining and executing a recursive function. NOTE: it has been reported by a reliable third party that some later versions are also affected.
https://exchange.xforce.ibmcloud.com/vulnerabilities/25704
http://www.vupen.com/english/advisories/2006/1290
http://www.securityfocus.com/bid/22766
http://www.securityfocus.com/archive/1/431018/100/0/threaded
http://www.securityfocus.com/archive/1/430742/100/0/threaded
http://www.securityfocus.com/archive/1/430598/100/0/threaded
http://www.securityfocus.com/archive/1/430453/100/0/threaded