ImageIO in Apple Safari before 5.0.6 on Windows does not properly address re-entrancy issues, which allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a crafted TIFF file.
http://support.apple.com/kb/HT4981
http://support.apple.com/kb/HT4808
http://lists.apple.com/archives/security-announce/2011//Jul/msg00002.html
http://lists.apple.com/archives/Security-announce/2011//Oct/msg00000.html