Computer security researchers said on Wednesday they have discovered a vulnerability in Adobe's ubiquitous Acrobat Reader software that allows cyber-intruders to attack personal computers through trusted web links.

Virtually any website hosting Portable Document Format, or PDF, files are vulnerable to attack, according to researchers from Symantec and VeriSign's iDefense Intelligence.

The attacks could range from stealing cookies that track a user's web browsing history to the creation of harmful worms, the researchers said.