description: Use-after-free vulnerability in WebKit in Apple Safari before 5.0 on Mac OS X 10.5 through 10.6 and Windows, and before 4.1 on Mac OS X 10.4, allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via vectors related to the Cascading Style Sheets (CSS) run-in property and multiple invocations of a destructor for a child element that has been referenced multiple times.