There are ways to attack an AESA radar on a dedicated one-to-one basis, says Lt. Gen. Herbert Carlisle, the Air Force’s deputy chief of staff for operations. However, that vulnerability can be mitigated by the fusion of multiple radars. If several aircraft with AESAs network themselves together, the radar being attacked can shut down and rely on information available on the network. Another option is to switch to infrared or electro-optical sensors.
Great idea. That is, if the network (which can be jammed or geo-located) is even running. And, you might not be too stealthy if you are an emitting network node.
As for infra-red, that is one of the reasons the Navy is fielding a hybrid center-line fuel tank with an infra-red search and track sensor on the front of it for the Super Hornet. The output from this sensor will be fused in the cockpit display.
The F-35 should have some infra-red capability as stock equipment. If it works. However, the F-35 has other survivability issues.
As for the vulnerabilities of radar systems in general, I don't know. This can be an interesting read which goes over some of the science behind radars in fighter aircraft.