Apple has issued an update for the Shellshock Bash vulnerability for OS X Lion, Mountain Lion and Mavericks.
The update, which is available directly from Apple and not delivered through the Mac App Store, patches the version of Bash included in OS X. Lion users can download the update here, Mountain Lion users, here.
Shellshock became public last week and although its main target is web servers, the inclusion of Bash in OS X gave plenty of Mac users a reason to feel uncomfortable. Apple released a statement saying that although the vast majority of Mac users would not be affected by the vulnerability, it would be issuing a patch for "experienced UNIX users."
Apple has patched the bash vulnerability for OS X Lion, Mountain Lion and Mavericks http://t.co/DcvZJmBa56 #shellshock— Tim Bradshaw (@tim) September 29, 2014
According to Apple's security release notes for this patch, it protects against the first two common vulnerabilities and exposures (CVE) associated with Shellshock. Six CVEs related to Shellshock have cropped up in the last few days.
If you use your Mac for a web server -- even as a localhost -- we'd recommend installing this update. Please note that at this time, Apple hasn't released an update for the OS X Yosemite beta. We imagine that the update will probably be rolled into the next Yosemite beta version, which is expected for release on Tuesday.