Are there any test steps for this advisory in order to prove the gateway is no longer vulnerable ?
As the vulnerability was at the OS level ensuring that the gateways have the latest platform patches will ensure that the gateways are protected. As for the attack vector, the following sites outline how to exploit this flaw: https://access.redhat.com/security/vulnerabilities/speculativeexecution and Meltdown and Spectre
Sincerely,
Stephen Hughes
CA Support