GnuCITIZEN has posted a detailed FAQ about a newly found Flash uPNP hack which could eventually lead the attacker to control a victim's router, regardless of the brand and model of the device.
The attack does not rely on any vulnerabilities within Flash but rather on the relationship between Flash and uPNP, a set of protocols that allow a device to poll continuously to find out whether devices - like cameras, printers etc - are hot-plugged in the network.
GnuCitizen details how the attack might take place on their website and although this is only a proof of concept, any capable hacker should be able to implement this straight away.
The attack does not depend on what platform or what browser you are using and affects even the latest Flash player.
There are only three ways to protect your network from a Flash uPNP attack: (a) disable uPNP (b) disable flash (c) disconnect altogether from the internet.
However, as the author of the FAQ stresses, " it is very likely that the same attack can be performed by other types of Web technologies [aside from Flash]."
Thinkbroadband summarises the issue nicely: "This problem with UPnP arises because it does not have an authentication procedure built into the protocol. So disabling it completely seems to be the only sure fire solution."