Apple Computer has fixed five security flaws in its Mac OS X operating system.
Security software company Symantec said the flaws allowed denial-of-service attacks to be launched and user systems to be taken over.
At the moment, said Symantec, no exploit code for the flaws was circulating on the internet, but Apple urged users to update their systems as soon as possible.
Apple fixed other security bugs in Mac OS X and QuickTime last month.
The Mac OS X 10.4.7 update also delivers some improvements to the operating system and fixes minor technical problems related to the operating system’s Mail, Finder and iChat features.
Apple plans to unveil Mac OS 10.5, codenamed Leopard, at its annual developer conference in August.