According to various studies, the majority of the security problems arising due to adobe software occur not due to bugs in flash software as per the general belief but because of the use of maliciously crafted PDF to use the holes in adobe reader and this amounts to no less than 80% of all the problems.

This is a considerable rise from the previous high of about 60% in the last year, and presents a significant risk. On the flip side, the flash related risks dropped from about 40% to just about 18% , this might actually indicate the preference of malware authors for PDF over flash and also probably due to the widespread use of the PDF files in recent times.

Probably its time that adobe and users take their security seriously and users still have the option of 3rd party PDF readers / creators.