That was fast

[JPnyc]

http://dvlabs.tippingpoint.com/blog/2008/06/18/vulnerability-in-mozilla-firefox-30?1=1

[puterfixer]

Everyone jumped at calling it a "zero day vulnerability"... I beg to differ. It appears to be a vulnerability found in 2.x which was migrated to 3.0 as well, and coincidentally was announced at the same time. If it worked solely on 3.0, then yes, I'd agree it was a serious ZD vulnerability.