PHP Other Vulnerability - CVE-2007-1700
The session extension in PHP 4 before 4.4.5 and PHP 5 before 5.2.1 calculates the reference count for the session variables without considering the internal pointer from the session globals which allows context-dependent attackers to execute arbitrary code via a crafted string in the session_register after unsetting HTTP_SESSION_VARS and _SESSION which destroys the session data Hashtable.