Apple patched QuickTime late Wednesday to fix 11 flaws in the Mac and Windows versions of the media player. All but two of the bugs could be used by hackers to hijack users' machines.

QuickTIme 7.4.5 -- the third security update Apple has released for the program so far in 2008 -- plugs vulnerabilities in how the player handles Java and PICT image files, parses some data objects, and uses Animation codec content, among others. Nine of the 11 bugs patched Wednesday were characterized by Apple as allowing "arbitrary code execution," a phrase the company uses to describe the most serious threats. Unlike other vendors such as Microsoft or Oracle Corp, Apple doesn't rank the bugs it fixes with a scoring or labeling system.

Many of the vulnerabilities can be exploited if attackers are able to trick users into visiting malicious Web sites or open rigged files. Of those in the second category, Apple warned that some of the bugs could be triggered by malicious movie or PICT files.

One flaw and possible attack vector was explained by Apple this way: "A memory corruption issue exists in QuickTime's handling of movie media tracks. Viewing a maliciously crafted movie file may lead to an unexpected application termination or arbitrary code execution," the company said.

Three of the 11 vulnerabilities affect the Windows version of QuickTime only; the remaining eight exist in both the Mac and Windows editions, Apple said in the notes it released along with the patched program.

More than half of the bugs were credited to 3Com's TippingPoint, and its Zero Day Initiative, a well-known bug bounty program. TippingPoint and ZDI have been in the news of late, as the former sponsored the "PWN To OWN" hacker challenge that took place last week at the CanSecWest security conference. The latter paid out US$15,000 in cash prizes to two hackers who compromised laptops running Mac OS X and Windows Vista SP1.

Before Wednesday, Apple had updated QuickTime twice in 2008 -- in January and again in February -- to fix a total of five flaws. Counting the 11 of 7.4.5, Apple is on an annual pace to plug more than 40 vulnerabilities in the program. In 2007, the company patched 34 vulnerabilities in its multimedia player program.

Mac users can upgrade to QuickTime 7.4.5 using the operating system's built-in Software Update feature, while Windows users can either download the new edition from the Apple site or use the optional Windows update tool.