Time-of-check Time-of-use (TOCTOU) Affecting kernel-rt-debug-kvm package, versions *


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.35% (73rd percentile)

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  • Snyk IDSNYK-RHEL8-KERNELRTDEBUGKVM-1569792
  • published26 Aug 2021
  • disclosed31 Mar 2021

Introduced: 31 Mar 2021

CVE-2021-29657  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 kernel-rt-debug-kvm.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-kvm package and not the kernel-rt-debug-kvm package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.

CVSS Scores

version 3.1