According to DefenseCode they are able to remotely attain root access (read FULL access) to Cisco Linksys WRT54GL routers, and possibly any Linksys router running 4.30.14 or below.

With over 70 million Linksys routers out there, and due to the extreme hazards of this exploit, we feel it’s important to let you know about it, even though very little can be done until Cisco issues a patch.

In the meantime, if you run a stock Linksys router, do not enter any sensitive communications unless you’re on an HTTPS site. This means FTP if you’re a web admin, or accessing blogs, and other sites you may have to sign in on that are not https secured.

Unfortunately, the XVU Drive will do nothing to aid in your security against this hack. We’re simply informing our customers so they’re aware and can install a patch as soon as it’s available.

Stay safe.