Bug 1595143 (CVE-2018-12904) - CVE-2018-12904 kernel: kvm: nVMX: missing privilege check allows privilege escalation in nested virtualization
Summary: CVE-2018-12904 kernel: kvm: nVMX: missing privilege check allows privilege es...
Alias: CVE-2018-12904
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1595145 1595146
Blocks: 1595148
TreeView+ depends on / blocked
Reported: 2018-06-26 08:42 UTC by Adam Mariš
Modified: 2021-02-17 00:04 UTC (History)
43 users (show)

Fixed In Version: kernel 4.17.2
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2019-07-12 13:05:42 UTC

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Description Adam Mariš 2018-06-26 08:42:45 UTC
It was found that KVM virtualizing another hypervisor as L1 VM does not verify that VMX instructions from L1 VM (which trigger a VM exit and are emulated by L0 KVM) are coming from ring 0. This means that a normal user space program running in the L1 VM can trigger KVMs VMX emulation which gives a large number of privilege escalation vectors. This issue happens only if L2 guest is running, since VMX emulation code checks for the guests CR4.VMXE value.

This allows attacker in L2 guest to break out e.g. by exploiting a bug in L1 qemu process and using this bug for privilege escalation on the L1 system.

Bug report:


Upstream patch:


Comment 1 Adam Mariš 2018-06-26 08:43:47 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1595146]

Comment 3 Adam Mariš 2018-06-27 12:30:59 UTC
CVE known via:


Comment 4 Prasad J Pandit 2018-08-29 18:54:47 UTC

This issue does not affect the versions of the kernel package as shipped with
Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG 2.

Comment 7 Product Security DevOps Team 2019-07-12 13:05:42 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):


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