The concern of Adobe Flash allowing cookies that are not controlled by your browser, to be stored is discussed in the articles here. First, second, third.
Jim Hamm sends this info: "I have read about this previously, and when I checked the cookies in my Mac using Adobe's Settings Manager (third link) I was amazed at the number of cookies I had, and I did not recognize many of the names. On several, I recognized the name but, to my remembrance (which, admittedly, can be shaky), I had never visited the website.
"I deleted all of them, and went to the Global Privacy Settings panel and set it to block all cookies. Unfortunately, it seems all this does is block a website from accessing a camera or microphone.
"I'm not clear if one can set Adobe Flash to block cookies completely and permanently. If someone does know, I'd appreciate your letting me know how to make this setting.
"As a general statement, I'm not concerned so much about cookies that I might pick up in my browser -- and I can set Safari to block cookies. Cookies do serve a useful purpose in many cases and, from what I've read, are not malware as such. But I'm not clear as to why Adobe should capture these cookies. According to the article, 'Adobe condemns the practice of using Local Storage to back up browser cookies for the purpose of restoring them later without user knowledge and express consent.' "