The Zend Engine in PHP 4.x before 4.4.7, and 5.x before 5.2.2, allows remote attackers to cause a denial of service (stack exhaustion and PHP crash) via deeply nested arrays, which trigger deep recursion in the variable destruction routines.

Double free vulnerability in the unserializer in PHP 4.4.5 and 4.4.6 allows context-dependent attackers to execute arbitrary code by overwriting variables pointing to (1) the GLOBALS array or (2) the session data in _SESSION. NOTE: this issue was in

Integer overflow in PHP 4.4.4 and earlier allows remote context-dependent attackers to execute arbitrary code via a long string to the unserialize function, which triggers the overflow in the ZVAL reference counter.