Adobe released a critical Flash update on June 10th. If you haven't seen it yet, this is the update notification:
Do you know what Flash version you have installed? No? Then use Adobe's version test page.
Once you have the current version, you may also wish to adjust your configuration. Flash's settings are rather curious as the controls themselves aren't located on the computer but are instead accessed through a Flash object hosted by Adobe.
Adobe: "The Settings Manager is a special control panel that runs on your local computer but is displayed within and accessed from the Adobe website. Adobe does not have access to the settings that you see in the Settings Manager or to personal information on your computer."