Secunia vulnerability monitoring service rated the flaws "extremely critical" in an advisory today.
In its latest update, the computing giant offers fixes for three flaws, which include a problem with the Safari web browser that could allow arbitrary code to be executed when a user visits a malicious web site.
The first update of the year, issued earlier this month, "addressed an issue where Safari could automatically open a file that appears to be a safe file type, such as an image or a movie, but is actually an application," according to Apple.
This latest patch "provides additional checks to identify variations of the malicious file types addressed in (the first security update) so that they are not automatically opened."
The update also removes unnecessary warnings for Mac OS X users who download safe file types, such as Word documents and folders containing custom icons.