Software Engineering Institute

According to Apple:

Two separate stack buffer overflows exist in the AirPort wireless driver's handling of malformed frames.
By transmitting a specially-crafted 802.11 frame to a vulnerable system, an attacker may be able to trigger the overflow. Note that the attacker needs to have 802.11 wireless connectivity to the vulnerable system to exploit this vulnerability.

Because device drivers execute with ring 0 privileges, this means that exploitation of device drivers can lead to full, unrestricted access to the vulnerable system.

It is important to note that because the vulnerability exists at a lower network layer than TCP/IP, software firewalls, anti-virus software, and host-based IDS or IPS systems may not protect against this vulnerability.

For information on affected versions of OS X refer to Apple Security Update 2006-005.

An unauthenticated attacker may be able to execute arbitrary code with kernel (ring 0) privileges.

Apply updates from Apple
Apple has released updates that address this issue. See Apple Security Update 2006-005 for more details.

Disable the affected wireless adapter
Turning off the wireless adapter can mitigate this vulnerability. To turn off the wireless card, follow the instructions found in Apple's knowledgebase:

Turning AirPort off

Turn your AirPort Card off when you're in situations where radio communication may be prohibited, such as in an airplane or at a hospital.
1.\tOpen the Internet Connect application and click AirPort in the toolbar.
2.\tClick Turn AirPort Off.

If you have disabled the AirPort port in Network preferences, then your AirPort Card is already turned off. To disable the AirPort port, choose Network Port Configurations from the Show pop-up menu and deselect the AirPort checkbox.