high
8.8
CWE
862
Advisory Published
CVE Published
CVE Published
Updated

CVE-2021-3653

First published: Mon Jul 19 2021(Updated: )

A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "int_ctl" field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.

Credit: secalert@redhat.com secalert@redhat.com

Affected SoftwareAffected VersionHow to fix
redhat/kernel-rt<0:3.10.0-1160.45.1.rt56.1185.el7
0:3.10.0-1160.45.1.rt56.1185.el7
redhat/kernel<0:3.10.0-1160.45.1.el7
0:3.10.0-1160.45.1.el7
redhat/kernel<0:3.10.0-327.101.1.el7
0:3.10.0-327.101.1.el7
redhat/kernel<0:3.10.0-514.95.1.el7
0:3.10.0-514.95.1.el7
redhat/kernel<0:3.10.0-693.95.1.el7
0:3.10.0-693.95.1.el7
redhat/kernel<0:3.10.0-957.84.1.el7
0:3.10.0-957.84.1.el7
redhat/kernel<0:3.10.0-1062.59.1.el7
0:3.10.0-1062.59.1.el7
redhat/kernel-rt<0:4.18.0-305.19.1.rt7.91.el8_4
0:4.18.0-305.19.1.rt7.91.el8_4
redhat/kernel<0:4.18.0-305.19.1.el8_4
0:4.18.0-305.19.1.el8_4
redhat/kernel<0:4.18.0-147.56.1.el8_1
0:4.18.0-147.56.1.el8_1
redhat/kernel-rt<0:4.18.0-193.68.1.rt13.118.el8_2
0:4.18.0-193.68.1.rt13.118.el8_2
redhat/kernel<0:4.18.0-193.68.1.el8_2
0:4.18.0-193.68.1.el8_2
redhat/kernel<5.14
5.14
Linux Kernel>=2.6.30<4.4.282
Linux Kernel>=4.5<4.9.281
Linux Kernel>=4.10<4.14.245
Linux Kernel>=4.15<4.19.205
Linux Kernel>=4.20<5.4.142
Linux Kernel>=5.5<5.10.60
Linux Kernel>=5.11<5.13.12
Linux Kernel=5.14-rc1
Linux Kernel=5.14-rc2
Linux Kernel=5.14-rc3
Linux Kernel=5.14-rc4
Linux Kernel=5.14-rc5
Linux Kernel=5.14-rc6
Red Hat Enterprise Linux=7.0
Debian Debian Linux=9.0
debian/linux
5.10.223-1
5.10.226-1
6.1.123-1
6.1.119-1
6.12.11-1
6.12.12-1

Remedy

This vulnerability can be mitigated by disabling the nested virtualization feature: ``` # modprobe -r kvm_amd # modprobe kvm_amd nested=0 ```

Remedy

https://bugzilla.redhat.com/show_bug.cgi?id=1983686

Remedy

https://www.openwall.com/lists/oss-security/2021/08/16/1

Remedy

Disable nested virtualisation when loading the KVM AMD module: modprobe kvm_amd nested=0

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the severity of CVE-2021-3653?

    CVE-2021-3653 has been rated as a medium severity vulnerability.

  • How do I fix CVE-2021-3653?

    To remediate CVE-2021-3653, update to the specified fixed kernel versions as released by Red Hat.

  • Which systems are affected by CVE-2021-3653?

    CVE-2021-3653 impacts specific versions of the Red Hat kernel and kernel-rt packages.

  • Can CVE-2021-3653 be exploited remotely?

    Yes, CVE-2021-3653 can be exploited by an attacker with access to a nested virtual machine environment.

  • What type of vulnerability is CVE-2021-3653?

    CVE-2021-3653 is a flaw in the AMD code for KVM's support of SVM nested virtualization.

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