Yes, but a weird machine program may be able to turn an extremely unlikely exploit into a guaranteed one; for example rowhammer, or heating up the hardware to i

Yes, but a weird machine program may be able to turn an extremely unlikely exploit into a guaranteed one; for example rowhammer, or heating up the hardware to induce bit flips, or simply making enough vulnerable objects that when a "cosmic ray" bit flip eventually occurs, it will immediately result in a breakout. Or purely in software, by arranging for hash collisions that would be prohibitively unlikely to occur in a normal execution. Even if it can't achieve breakout, a weird machine program may still be able to observe its host and leak information to an attacker-controlled server via timing attacks. I think the ExSpectre attack mentioned near the end is related to this.