WebKit.dll in WebKit, as used in Safari.exe 4.531.9.1 in Apple Safari, allows remote attackers to cause a denial of service (application crash) via JavaScript that writes <marquee> sequences in an infinite loop.
http://www.vupen.com/english/advisories/2011/0212
http://secunia.com/advisories/43068
http://lists.opensuse.org/opensuse-security-announce/2011-01/msg00006.html