The Broadcom BCMWL5.SYS wireless device driver is vulnerable to a stack-based buffer overflow that can lead to arbitrary kernel-mode code execution. This particular vulnerability is caused by improper handling of 802.11 probe responses containing a long SSID field. The BCMWL5.SYS driver is bundled with new PCs from HP, Dell, Gateway, eMachines, and other computer manufacturers. Broadcom has released a fixed driver to their partners, which are in turn providing updates for the affected products. Linksys, Zonet, and other wireless card manufactures also provide devices that ship with this driver.
More details and proof of concept (exploit) at http://projects.info-pull.com/mokb/MOKB-11-11-2006.html.