The update addresses a number of wide-ranging issues, some of which can be exploited to execute arbitrary code, such as holes in Core Graphics, CoreMedia, DirectoryService and Help Viewer. There also were fixes for four bugs in QuickTime.
Among the more intriguing fixes is one for a much-discussed problem within online forums that causes data to be wiped from machines if a user logs in using a guest account. Also, the update patched a race condition vulnerability in the Login Window that could allow a user to sign on without providing a password.
Users still running Mac OS X 10.5, known as Leopard, also are encouraged to update.