The attack is apparently delivered via maliciously crafted PDF documents, and affects Mac OS X, Unix and Windows. Mac and Unix users, however, will only experience application crashes, according to Adobe.
- Launch Acrobat or Adobe Reader.
- Choose Acrobat > Preferences or Adobe Reader > Preferences.
- Click OK.
It appears that examples of PDF documents that can take advantage of the flaw are in the wild, and Adobe is considering the threat critical. The company is, however, only promising a patch by January 12.