The JSON_parser function (ext/json/JSON_parser.c) in PHP 5.2.x before 5.2.9 allows remote attackers to cause a denial of service (segmentation fault) via a malformed string to the json_decode API function.
https://www.redhat.com/archives/fedora-package-announce/2009-May/msg01465.html
https://www.redhat.com/archives/fedora-package-announce/2009-May/msg01451.html
http://www.ubuntu.com/usn/USN-761-2
http://www.redhat.com/support/errata/RHSA-2009-0350.html
http://www.php.net/releases/5_2_9.php
http://www.openwall.com/lists/oss-security/2009/04/01/9
http://www.mandriva.com/security/advisories?name=MDVSA-2009:090
http://www.debian.org/security/2009/dsa-1789
http://www.debian.org/security/2009/dsa-1775
http://support.apple.com/kb/HT3865
http://secunia.com/advisories/36701
http://secunia.com/advisories/35685
http://secunia.com/advisories/35306
http://secunia.com/advisories/35007
http://secunia.com/advisories/35003
http://secunia.com/advisories/34933
http://secunia.com/advisories/34830
http://secunia.com/advisories/34770
http://lists.opensuse.org/opensuse-security-announce/2009-07/msg00002.html
http://lists.apple.com/archives/security-announce/2009/Sep/msg00004.html
http://cvs.php.net/viewvc.cgi/php-src/ext/json/JSON_parser.c?r1=1.1.2.14&r2=1.1.2.15