Adobe has acknowledged that an internal screw-up caused a potentially dangerous Flash Player flaw to remain unpatched for more than 16 months after it was first reported by an external security researcher. Adobe s mea-culpa follows the public release of proof-of-concept code demonstrating a Flash Player browser plug-in crash. The issue was fixed in Flash Player 10.1 beta but was erroneously tagged to be fixed in the next release which meant that four different Flash Player 9 patches were released without this fix.
Source: https://threatpost.com/adobe-error-leaves-flash-flaw-unpatched-16-months-020910/73516/