CVE-2021-29657

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    CVE-2021-29657

    Published: 22 Jul 2021Last Modified: 16 Apr 2026

    Summary:

    Details: 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.

    References: http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html, https://security.netapp.com/advisory/ntap-20210902-0008/, https://bugs.chromium.org/p/project-zero/issues/detail?id=2177, https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: N/A

    Events:

    Introduced- None
    Fixed -None

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2021-29657 | CVE-DB