They are released really on an as needed basis. I say this because there really isn't a set schedule that I see. I would suggest getting on the mailing list for the updates.

5. Subscribe to the Product Alert Tool for IPS Related Field Issues

Interested in knowing the latest on field notices, product alerts, and end-of-sale information relating to your IDS and IPS hardware? We have recently updated the Cisco Product Alert Tool to include IDS and IPS appliances.

Simply visit: http://tools.cisco.com/Support/PAT/do/ViewMyProfiles.do and follow these steps:

- Select Create a new Alert Profile.

- Name your profile anything you would like.

- Under Select Your Product, select: Intrusion Prevention System

- Click Add so that "Intrusion Prevention System" is added to the "Products in your profile" list

- Select the message types you wish to receive

- Confirm your email address

- Click Submit.

You'll notice updates come out more frequently as exploits and vulnerabilities become known.