UBUNTU-CVE-2021-29657

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    UBUNTU-CVE-2021-29657

    Published: 3 Apr 2021Last Modified: 4 Feb 2026
    Upstream:
    CVE-2021-29657
    Aliases:
    USN-4948-1

    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: https://ubuntu.com/security/CVE-2021-29657, https://git.kernel.org/linus/a58d9166a756a0f4a6618e4f593232593d6df134, https://ubuntu.com/security/notices/USN-4948-1, https://www.cve.org/CVERecord?id=CVE-2021-29657

    Affected packages

    Package

    Name: linux-hwe-edge

    Purl: pkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=xenial

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    4.8.0-28.30~16.04.1
    4.8.0-30.32~16.04.1
    4.8.0-32.34~16.04.1
    4.8.0-34.36~16.04.1

    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
    UBUNTU-CVE-2021-29657 | CVE-DB