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> […] VMs are not magically different: they are better isolated, but VMs on the same host still share the host in common.

VMs are not different due to 'magic' but through hardware assist with things like Intel VT-x and AMD-V:

* https://en.wikipedia.org/wiki/X86_virtualization#Hardware-as...

* https://blog.lyc8503.net/en/post/hypervisor-explore/

* https://binarydebt.wordpress.com/2018/10/14/intel-virtualisa...

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You are obviously right that these are similar in principle: VM isolation exploit would lead to the same exposure like container-related isolation exploits.

VMs are considered vastly better because the surface area where exploits can happen is smaller and/or better isolated within the kernel.

If you are arguing the latter is not true — and we are all collectively hand-waving away big chunk of the surface area so that may be the case — it would help to be explicit in why you believe an exploit in that area is similarly likely?

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I would say it's the fact that "not a security boundary" appears to be a pass/fail statement, whereas the reality is more like a security continuum, along which VMs are further than containers.
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Containers are a security boundary, yes.

> A CVE next week that allows corruption of host state that affects eg every VM under a particular hypervisor will be no less damaging than this CVE is to containers

Yeah this almost never happens though whereas Linux privesc is 10x a day.

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