Apple Computer has released its third major patch this year for the OS X operating system fixing 31 software vulnerabilities. However, a security researcher said that the patch does not cover all of them.

Security Update 2006-003 was published on Apple's website and includes software fixes for holes in OS X, the Safari Web browser, and Mac components for viewing image and video files. The patch includes fixes for flaws identified by independent researcher Tom Ferris in April. However, Ferris says the latest patch doesn't cover other critical holes he reported to Apple, and that he may soon publish the details of those flaws on his website.

An Apple spokesman did not immediately respond to a request for comment.

The patches, which come two days after Microsoft released its monthly security fixes, underscore the changing security climate for Mac systems, which are a small fraction of the computer population, but are under increasing scrutiny for security holes.

Among the flaws Apple fixed are an integer overflow in the processing of JPEG files by OS X systems, prior to Version 10.4. These could allow attackers to harbor malicious code in image files; the code executes when the file is viewed.

Another flaw affects Quicktime Streaming Server on some versions of OS X and could allow attackers to use malicious RTSP (Realtime Streaming Protocol) requests to trigger a buffer overflow on the server. Other holes would allow attackers to use e-mail messages, Macromedia Flash files or malicious shortcuts to take control of Mac systems.

Ferris said there were still holes in Safari, QuickTime, and the iTunes application that he reported to Apple but were not patched in the latest release. He did not publish details of those holes on his Web site in April, but he described them as critical flaws that allow remote code execution. He also said he has found new holes in OS X affecting TIFF format files and BOMArchiver, an application used to compress files. He did not provide details about the flaws or proof of their existence.

Officially, Apple downplays security holes in its products and new OS X attacks - which are still rare compared to those targeting Windows systems. But some security industry insiders have suggested that the company should appoint a chief security officer to coordinate the company's response to security.