alt Hacker NewsNope. The exploit compromises the host kernel. The researchers built an unconventional exploit chain in which they used the host kernel compromise to compromise the host firecracker userspace code, but I see no fundamental reason they couldn't have compromised something else in the host kernel.
Wait, this is also presumably true, come to think of it. I'm a little fuzzy because they document the memory disclosure primitive carefully but not the memory writes they also got from it --- but whatever those are, they're hitting kernel memory? But the exploit they're describing here gets code execution out of Firecracker itself, not the kernel.