Beware Adobe Acrobat users!

The security researcher who discovered a recently patched QuickTime flaw affecting the Firefox browser says he has found a similar serious flaw in Adobe Systems Inc.'s PDF file format.

"Adobe Acrobat/Reader PDF documents can be used to compromise your Windows box. Completely!!! Invisibly and unwillingly!!!," wrote Petko D. Petkov, in a blog posting. "All it takes is to open a PDF document or stumble across a page which embeds one."

Petkov confirmed this issue on Adobe Reader 8.1 on Windows XP and he said he would not disclose the code that exposes how this attack works until Adobe provides a patch for the problem, but he has already sent other software developers scrambling for bug fixes over the past week.