Authorize.Net itself is not vulnerable to POODLE, but we are making changes to our systems to assure that we are providing our merchants and their customers with the highest degree of security possible.
Most modern shopping carts do not use this old technology in their solutions-in general, POODLE will only affect solutions that are older and use SSLv3. But again, because we do not control which method your systems use for transaction processing, we are not able to advise whether or not this change will affect you site or solution. We strongly urge you to contact your web developer or payment solution provider to find out for sure.
NetStores tested the Authorizenet Compatibility and Setup a sandbox as requested at: