QEMU has a secure subset, and the kitchen sink around it. For a properly configured VM, even better if wrapped in SELinux, it is not easy to escape even QEMU.

In this case, of the four bugs it found:

* Two were in libslirp, which is not part of that subset; user mode networking these days should use passt (https://passt.top/), an insanely cool hack that does user mode networking at many Gb/s and is secure

* One (which had already been patched upstream) was in VGA emulation; it is borderline but I think it should indeed count as being part of the secure subset. On the other hand it wasn't usable in the configuration under test because it was correctly configured without a VGA.

* The VAPIC bug is letting a guest do things that it shouldn't do such as bypassing secure boot (and in this case facilitating the exploitation of a KVM bug), but is not a full guest-to-host escape and is not specific to QEMU being written in C.

So the real issue here was not QEMU but libslirp. And in this case it was KVM that turned out to have the worst bugs, not QEMU. Crossing fingers, the initial wave of AI-assisted security reports seems to have slowed down for KVM on x86.