WebKit, as used in Apple iOS before 6.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted web site, a different vulnerability than other WebKit CVEs listed in APPLE-SA-2013-01-28-1.
http://support.apple.com/kb/HT5642
http://lists.apple.com/archives/security-announce/2013/Mar/msg00003.html
http://lists.apple.com/archives/security-announce/2013/Jan/msg00000.html