The latest vulnerability is called Filet-o-Firewall and combines a number of vulnerabilities and weaknesses in routing protocols and browsers to expose networked devices behind a firewall to the open Internet. Attacks can happen in fewer than 20 seconds and any router running UPnP is at risk. The vulnerability is logic based and does not reside in a specific piece of code. A list of affected routers is being compiled on the website, and the researcher is asking for help in adding vulnerable devices to the list.
Source: https://threatpost.com/upnp-trouble-puts-devices-behind-firewall-at-risk/114493/