Kernel exploits. Containers logically isolate resources but they’re still effectively running as processes on the same kernel sharing the same hardware. There was one of those just last year: blog.aquasec.com/cve-2022-0185-linux-kernel-conta…
Virtual machines are a whole other beast because the isolation is enforced at the hardware level, so you have to exploit hardware vulnerabilities like Spectre or a virtual device like a couple years ago some people found a breakout bug in the old floppy emulation driver that still gets assigned to VMs by default in QEMU.