Multiple use-after-free vulnerabilities in WebKit, as used in Apple Safari before 4.1.3 and 5.0.x before 5.0.3, Google Chrome before 5.0.375.127, and webkitgtk before 1.2.6, allow remote attackers to execute arbitrary code or cause a denial of service (application crash) via vectors related to improper handling of MIME types by plug-ins.