The memory_limit functionality in PHP 4.x up to 4.3.7, and 5.x up to 5.0.0RC3, under certain conditions such as when register_globals is enabled, allows remote attackers to execute arbitrary code by triggering a memory_limit abort during execution of the zend_hash_init function and overwriting a HashTable destructor pointer before the initialization of key data structures is complete.
https://exchange.xforce.ibmcloud.com/vulnerabilities/16693
http://www.gentoo.org/security/en/glsa/glsa-200407-13.xml
http://www.debian.org/security/2005/dsa-669
http://marc.info/?l=bugtraq&m=109181600614477&w=2
http://marc.info/?l=bugtraq&m=109051444105182&w=2