On Wednesday, Cisco revealed that a group of Chinese government-backed hackers is exploiting a vulnerability to target its enterprise customers who use some of the company’s most popular products.Cisco has not said how many of its customers have already been hacked, or may be running vulnerable systems. Now, security researchers say there are hundreds of Cisco customers who could potentially be hacked. Piotr Kijewski, the chief executive of the nonprofit Shadowserver Foundation that scans and monitors the ...