There is a known UPnP vulnerability in some routers, its very serious and you should test your network see if you are affected (mine is O.K.)

 

Read more: http://www.reuters.com/article/2013/01/29/us-cybersecurity-bugs-idUSBRE90S06320130129

 

View more: http://twit.tv/show/security-now/389

 

Test yourself: https://www.grc.com (go to Services > ShieldsUP! and you will find a "instant UPnP exposure test" button)

With or without my software firewall (Outpost Free), my router is safe:

 

THE EQUIPMENT AT THE TARGET IP ADDRESS
DID NOT RESPOND TO OUR UPnP PROBES!

Here is a link to an article for some (non)susceptible Linksys routers http://homekb.cisco.com/Cisco2/ukp.aspx?vw=1&articleid=28341

 

This reconfirms to me that I am fine (I own a E2500)

Those who use custom firmware (such as DD-WRT) are also not affected by this security risk.

You can get a more detailed scan on this site, it tells you what version UPnP/OS your router has (needs Java)
 
http://netalyzr.icsi.berkeley.edu/
 
Here is why I am not affected
 

This device appears to run "POSIX UPnP/1.0 linux/5.60.127.2901".

 
A device that is affected shows this
 

This device appears to run "Linux/2.6.35.8, UPnP/1.0, Portable SDK for UPnP devices/1.6.6". This system may be vulnerable to CVE-2012-5958 and CVE-2012-5959

 
Portable SDK for UPnP Devices has been updated to resolve this issue