Apple has released its fifth Mac OS X security update of 2007 to patch a number of potential vulnerabilities. makes changes to CoreGraphics, iChat, VPN, BIND, crontabs, PPP, and other components, in most cases correcting problems that require either local user access or access to the Mac via a local network. However, several fixes are more important. An update to BIND prevents a possible remote denial of service attack (but because it reportedly overwrites the BIND launchd plist file, it may both turn BIND off and cause other changes to be lost, a potential problem for Mac OS X Server machines), a new version of fetchmail prevents possible disclosure of passwords, and a fix for CoreGraphics in Mac OS X 10.4 provides additional verification of PDF files to avoid possible crashes when opening maliciously crafted PDFs. The update is available via Software Update or for download in four varieties: for Mac OS X 10.4.9 as  and  installers; and for Mac OS X 10.3.9  and  systems.