The megapatch is thein three months. It deals with vulnerabilities in Apple's own software, as well as third-party components such as Adobe Systems' Flash Player, OpenSSH and MySQL. Sixteen of the vulnerabilities addressed by the update were previously released as part of .
The vulnerabilities pose varying risks to Macs. Several of the flaws could be exploited to gain full control over a Mac running the vulnerable component, according to Apple's advisory. Other holes are limited and could only be exploited to crash a Mac or used by somebody who already has access to a machine to elevate privileges, for example.
One focus of the patch is to fix eight vulnerabilities in the way Mac OS X handles disk images, files that when opened appear as a drive within the Macintosh Finder. Mounting a malicious image may lead to an error and could provide a means for an attacker to breach a Mac, Apple said.
Tuesday's update deals with nine vulnerabilities released as part of the in January and seven bugs disclosed in thein November. In earlier fix releases, Apple fixed several flaws identified during the projects.
While several of the vulnerabilities repaired by Apple's updates were previously known, it doesn't appear that any attacks that exploited the flaws actually occurred.
In addition to the Mac OS X patch, Apple issued a second update on Tuesday to fix a security bug in iPhoto that could expose Mac users to a serious attack. An attacker could craft a malicious "photocast" which, when opened, could compromise a Mac, Apple said in its alert. The Photocasts feature allows people to share pictures in iPhoto.
Tuesday's two releases bring Apple's total patch count for the year to seven. Microsoft, meanwhile, on Tuesday. However, it released with fixes for 20 vulnerabilities in February and four bulletins with fixes for 10 bugs in January.
The Apple patch can be downloaded and installed via the Software Update feature in Mac OS X, or from Apple Downloads.