In a notice on its corporate Web site today, Apple said it had released a wrap-up of general operating system stability and security improvements, including several that address malicious crafting exploits.

One new security update released today and incorporated into the version 10.5.4 package addresses a series of problems uncovered by, and attributed to, UK-based software developer and consultant James Urquhart, who himself does not claim to be a security engineer. A recent Secunia software advisory also credits Urquhart, who was also able to locate a problem with versions of Safari for Windows prior to version 3.1.2 (obviously not addressed by today's Mac OS X update).

Another problem with the handling of JavaScript arrays, which would normally be expected to terminate code execution, can lead to arbitrary code being executed instead. This latest operating system update addresses both of these issues.

Users who have already gotten an early glimpse of the terms of service for Apple's MobileMe -- announced earlier this month as the replacement for .Mac -- noted that the new service only supports OS X versions 10.4.11 (the last in that old series) or 10.5.4 and later. MobileMe is expected to be released July 11, which is why Mac users have been expecting 10.5.4 -- the newest system on which it depends -- to be released somewhat sooner.