Apple has released two security fixes for bugs in its OS X operating system.

The first patch plugs a hole that could allow hackers to crash a system by sending a specially crafted data packet. The flaw was first reported by the Northwestern University and effectively opens up the system for a denial of service attack.

A security notice on Apple's website claims that the flaw affects only the 10.4 versions of OS X and will not harm computers that sit behind a firewall or are otherwise protected through packet filtering. 

The other patch targets a bug in the 10.4 Tiger operating system that allows users inadvertently to overwrite standard widgets in Apple's Dashboard application.

Dashboard is an environment where small Java-based applications called widgets can run. The system comes with several pre-installed widgets including a calculator and weather forecaster, and users can download additional ones from the internet.

The update provides a warning when a user attempts to install a widget that has the same name as an existing one. Previously the new widget would run instead of the system widget, effectively making the original one inaccessible to the user.

This latest update moves OS X 10.4 to version 10.4.2 and is the third security update for the operating system since its release in April. 

Users can download the 44MB patch through the software update option in OS X or directly from Apple's website here.