Personally, I am not a fan of WordPress or software products that are completely open to anyone who can read their code - but that is me. But most of you are probably using WordPress, so it is critical that if you are and if you are using the All in One SEO Pack WordPress Plugin, that you patch it immediately.
There was a serious vulnerability found in the plugin that leaves your site open to major security issues.
Specifically, it leaves you open to privilege escalation and cross site scripting (XSS) attacks.
So go ahead and update it immediately or drop it completely.
Like I said, I personally dislike using software where anyone can read the code and find exploits with ease.
Forum discussion at WebmasterWorld.
