[kelnos]

No, because you're still in the container, and there's no route to the host's root from there.

If you can orchestrate a container escape from the container's "root", then you're on to something.

[wang_li]

This pollutes the page cache, which affects the entire host. Getting "root" in a rootless container may mean nothing. But if it attacked the ls, ps, cat, grep, etc. commands and any process outside the container invokes that command it runs the payload of the attacker. What if the payload of the attack is just the same attack to escalate to root? So now you have escaped the container and gained root.