The MadWifi driver provides support for Atheros based IEEE 802.11 Wireless Lan cards.
The driver does not properly process Channel Switch Announcement Information Elements, allowing for an abnormal channel change. The ieee80211_input() function does not properly handle AUTH frames and the driver sends unencrypted packets before WPA authentication succeeds.
A remote attacker could send specially crafted AUTH frames to the vulnerable host, resulting in a Denial of Service by crashing the kernel. A remote attacker could gain access to sensitive information about network architecture by sniffing unencrypted packets. A remote attacker could also send a Channel Switch Count less than or equal to one to trigger a channel change, resulting in a communication loss and a Denial of Service.
There is no known workaround at this time.
All MadWifi users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-wireless/madwifi-ng-0.9.3"