Toyota and Cyber Spies
It is important to note that I have seen no evidence that Chinese cyber-spies have infiltrated Toyota for the purpose of messing with the automotive control computer programs. Even if Chinese hackers, supposedly backed by the Chinese government, hacked Google and a few other large businesses, there is nothing to suggest that Toyota was one of them.
Of course, if the Chinese had gotten into Toyota, we probably wouldn't hear about it. Toyota would work with the Japanese Public Security Intelligence Agency (site) (site in English) and keep it quiet until they could hunt down as many of the bad guys as possible. Naturally, the CIA would work with them to minimize the trouble.
While hunting the bad guys, the Toyota coders would be scouring the software, looking for the malicious stuff. That way, they would be able to release a software patch for everyone and never have to admit that they were vulnerable to Red Menace. It would take some time to do this because modern automobiles have massive amounts of code in them. At the same time, they could never be sure that they weren't still vulnerable to further attack. All the security protocols would have to be in place before they could even start.
Again, I will point out that I have seen nothing to suggest that any of this has happened. Because of that, you should avoid discussing it with your friends, family, and co-workers. Don't let it affect your purchasing decisions regarding Toyotas. In particular, you should not let it increase any paranoia you may have about foreign cyber warfare.