"We have discovered a vulnerability in a number of providers that allows an attacker to expose the real IP address of a victim. "Port Fail" affects VPN providers that offer port forwarding and have no protection against this specific attack."
"This IP leak affects all users: The victim does not need to use port forwarding, only the attacker has to set it up."
It does not mention it in that article you posted, but one of the providers it affects is Private Internet Access. I got an email from them today