Prairiecrow's InsaneJournal

Details here:

http://asylums.insanejournal.com/macintosh/4021.html

and here:

http://dogemperor.insanejournal.com/225916.html

An excerpt:

From Adobe's April 8, 2008, bulletin:

Summary

Critical vulnerabilities have been identified in Adobe Flash Player that could allow an attacker who successfully exploits these potential vulnerabilities to take control of the affected system. A malicious SWF must be loaded in Flash Player by the user for an attacker to exploit these potential vulnerabilities. It is recommended users update to the most current version of Flash Player available for their operating system.

Due to the possibility that these security enhancements and changes may impact existing Flash content, content developers are advised to review this March 2008 Adobe Developer Center article to determine if the changes will affect their content, and to begin implementing necessary changes immediately to help ensure a seamless transition.

[...]

Affected software versions

Adobe Flash Player 9.0.115.0 and earlier, and 8.0.39.0 and earlier.

The blog entries I've linked to contain details, a link to Adobe's security bulletin, and a way to check which version of Flash Player your system is using.

Nasty stuff. Please spread the word.