Included in the update to Mac OS X 10.6.7 were patches for 36 vulnerabilities in Snow Leopard and Snow Leopard Server.
Apple also issued a security-only update for Mac OS X 10.5, better known as Leopard, that fixed 13 flaws in the 2007 operating system.
But most Mac users will be interested in the update because it's a prerequisite for Lion, the $30 Mac OS X upgrade Apple plans to sell through the Mac App Store in July.
At the top of the list of changes in 10.6.8, Apple put "Enhancements to the Mac App Store to get your Mac ready to upgrade to Mac OS X Lion."
Apple did not elaborate on what had changed in Mac App Store.
Because Lion will be sold solely through Apple's e-mart and weigh in at 4GB, some Mac users have complained that their Internet connection won't allow them to download the upgrade.
Other improvements and non-security bug fixes ranged from additional VPN reliability to a stability fix for Preview. Apple also shipped new signatures to detect and delete variants of the MacDefender "scareware" , worthless programs that pose as antivirus software and try to frighten people into paying up to $80 to get rid of persistent alerts.
Apple has delivered 12 different MacDefender signatures since it acknowledged the scareware problem in late May.
Mac OS X 10.6.8 will be the last non-security update to Snow Leopard. Once a new edition appears, Apple issues only vulnerability patches to the now-superseded version.
Tucked into Mac OS X 10.6.8 were patches for 36 security flaws, 29 of them tagged with Apple's traditional phrase "arbitrary code execution," the company's way of saying the flaws are critical. Apple does not assign severity rankings to vulnerabilities.
According to Apple's advisory , one of the bugs can be exploited by "drive-by" attacks that execute as soon as a victim browses to a malicious Web site with an unpatched Mac OS X. Eight of the vulnerabilities could be triggered simply by viewing a malformed file -- a Microsoft Office document in one case, a malicious image in most of the others -- that could be used to inject attack code.
Five of the image-related flaws were in QuickTime, Apple's media player.
Other components patched Thursday ranged from ATS (Apple Type Services), Mac OS X's font renderer to MySQL, the open-source database bundled with the server versions of Leopard and Snow Leopard. Oracle, which acquired the relational database three years ago, patched the MySQL bugs in February.
Apple also reported a bug in the App Store that in some circumstances could disclose the Apple ID used to sign into the download site. Interestingly, the patch applied to both Snow Leopard -- which already supports the Mac App Store -- as well as Leopard, which does not.
Yesterday's patch count was significantly lower than the last major Mac security update of March, when Apple fixed 55 flaws .
Although Apple will continue to provide security-only updates to Snow Leopard once Lion launches, the clock starts ticking for Leopard, which will be shuffled off the support list this year, if past practice is any guide.
In 2009, for example, Apple shipped the final security update for Mac OS X 10.4, aka Tiger, just a month after it released Snow Leopard.
Mac OS X 10.6.8 and the separate 2011-004 security update for Leopard can be downloaded at the Apple site or installed using the operating system's built-in update service.
The update downloads weigh in between 256MB and 474MB for the client versions of Leopard and Snow Leopard.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is firstname.lastname@example.org .
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This story, "Snow Leopard Updated in Anticipation of Lion" was originally published by Computerworld.