A vulnerability in Cisco WebEx browser extensions for Google Chrome and Mozilla Firefox could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the affected browser on an affected system. This vulnerability affects the browser extensions for Cisco WebEx Meetings Server, Cisco WebEx Centers (Meeting Center, Event Center, Training Center, and Support Center), and Cisco WebEx Meetings when they are running on Microsoft Windows. The vulnerability is due to a design defect in the extension. An attacker who can convince an affected user to visit an attacker-controlled web page or follow an attacker-supplied link with an affected browser could exploit the vulnerability. If successful, the attacker could execute arbitrary code with the privileges of the affected browser. The following versions of the Cisco WebEx browser extensions are affected: Versions prior to 1.0.12 of the Cisco WebEx extension on Google Chrome, Versions prior to 1.0.12 of the Cisco WebEx extension on Mozilla Firefox. Cisco Bug IDs: CSCvf15012 CSCvf15020 CSCvf15030 CSCvf15033 CSCvf15036 CSCvf15037.