A combination of holes disclosed by security researchers last month could have allowed an attacker to take over a vulnerable Macintosh, though no such exploits have been reported. Apple issued a partial fix last month, but security researchers had said that the Mac remained open to attack.
Apple executives had earlier pledged to release a more complete patch, calling the flaw the first critical security issue since Mac OS X was released three years ago.
"We fixed one part of what is a complex problem," Senior Vice President Phil Schiller said in an interview before the latest security update. "We're working on fixes to the other parts, and there will be more coming."
The patch, which was made available via Mac OS X's Software Update, attempts to prevent such problems by warning users when a program is being launched via the Internet that has not previously been run on the system. Apple also took other steps in Mac OS X and the Safari Web browser to try to keep unintended applications or files from being opened.
Apple said the update is being made available for those running version 10.3.4 of Mac OS X Panther and version 10.2.8 of Mac OS X Jaguar, as well as the corresponding server versions.
