Secunia

Armijn Hemel has reported a vulnerability in Linksys WRT54G, which can be exploited by malicious people to bypass certain security restrictions.

The vulnerability is caused due to missing authentication of UPnP AddPortMapping requests and missing validation of the InternalClient parameter of the request. This can be exploited by hosts on the local network to configure port forwarding settings on the device to forward incoming traffic to arbitrary hosts without requiring authentication.

Successful exploitation may allow the device to be configured to forward traffic that is received on specific ports on the external interface to another host on the Internet.

Solution
Update to firmware version 1.00.9 for WRT54Gv5.
Further details available in Customer Area

Provided and/or discovered by
Armijn Hemel

Changelog
Further details available in Customer Area

Original Advisory
http://www.securityview.org/how-does-the-upnp-flaw-works.html

Deep Links
Links available in Customer Area