Integer underflow in Help Viewer in Apple Mac OS X before 10.5 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a crafted help:topic URL that triggers a buffer overflow.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42716
http://www.vupen.com/english/advisories/2008/1697
http://www.us-cert.gov/cas/techalerts/TA08-150A.html
http://www.securityfocus.com/bid/29483
http://www.securityfocus.com/bid/29412
http://www.kb.cert.org/vuls/id/566875
http://securitytracker.com/id?1020138
http://secunia.com/advisories/30430
http://lists.apple.com/archives/security-announce/2008//May/msg00001.html