The most frustrating thing about this vulnerability is that you are at the mercy of your WebEx provider. That's because the WebEx provider's server automatically updates the WebEx client upon login to the latest version it has to distribute. And if the WebEx presenter is distributing a vulnerable client, you will be downgraded to a vulnerable client despite any attempt to upgrade to a nonvulnerable client.
Most WebEx presenters are on the WBS26 version of the software. Here's a quick snippet from the Cisco alert that will help you determine if you and your WebEx presenter are vulnerable.
"For the WBS 26 version: