The zend_hash_init function in PHP 5 before 5.2.1 and PHP 4 before 4.4.5, when running on a 64-bit platform, allows context-dependent attackers to cause a denial of service (infinite loop) by unserializing certain integer expressions, which only cause 32-bit arguments to be used after the check for a negative value, as demonstrated by an "a:2147483649:{" argument.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11092
https://exchange.xforce.ibmcloud.com/vulnerabilities/32709
http://www.vupen.com/english/advisories/2007/2374
http://www.vupen.com/english/advisories/2007/1991
http://www.ubuntu.com/usn/usn-424-2
http://www.ubuntu.com/usn/usn-424-1
http://www.securitytracker.com/id?1017671
http://www.securityfocus.com/archive/1/461462/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2007-0088.html
http://www.redhat.com/support/errata/RHSA-2007-0082.html
http://www.redhat.com/support/errata/RHSA-2007-0081.html
http://www.redhat.com/support/errata/RHSA-2007-0076.html
http://www.php.net/releases/5_2_1.php
http://www.php-security.org/MOPB/MOPB-05-2007.html
http://www.openpkg.com/security/advisories/OpenPKG-SA-2007.010.html
http://www.mandriva.com/security/advisories?name=MDKSA-2007:048
http://support.avaya.com/elmodocs2/security/ASA-2007-136.htm
http://support.avaya.com/elmodocs2/security/ASA-2007-101.htm
http://securityreason.com/securityalert/2315
http://security.gentoo.org/glsa/glsa-200703-21.xml
http://secunia.com/advisories/25850
http://secunia.com/advisories/25423
http://secunia.com/advisories/25056
http://secunia.com/advisories/24642
http://secunia.com/advisories/24606
http://secunia.com/advisories/24432
http://secunia.com/advisories/24421
http://secunia.com/advisories/24419
http://secunia.com/advisories/24322
http://secunia.com/advisories/24295
http://secunia.com/advisories/24284
http://secunia.com/advisories/24248
http://secunia.com/advisories/24236
http://secunia.com/advisories/24217
http://secunia.com/advisories/24195