CVE-2021-3656: Fedoraproject Fedora

High severity, CVSS 8.8. EPSS: 0.7% chance of exploitation in the next 30 days.

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 "virt_ext" field, this issue could allow a malicious L1 to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) 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.

Affected products

  • Fedoraproject Fedora: version 33 only; version 34 only
  • Linux Linux Kernel: from 4.13, before 4.14.245 (fixed in 4.14.245); from 4.15, before 4.19.205 (fixed in 4.19.205); from 4.20, before 5.4.142 (fixed in 5.4.142); from 5.5, before 5.10.60 (fixed in 5.10.60); from 5.11, before 5.13.12 (fixed in 5.13.12); version 5.14 only
  • Red Hat 3scale API Management: version 2.0 only
  • Red Hat Codeready Linux Builder: affected versions not specified
  • Red Hat Enterprise Linux: version 8.0 only
  • Red Hat Enterprise Linux Desktop: version 7.0 only
  • Red Hat Enterprise Linux Eus: version 8.1 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux For IBM Z Systems: version 7.0 only; version 8.0 only
  • Red Hat Enterprise Linux For IBM Z Systems Eus: version 8.1 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux For Power Big Endian: version 7.0 only
  • Red Hat Enterprise Linux For Power Little Endian: version 7.0 only; version 8.0 only
  • Red Hat Enterprise Linux For Power Little Endian Eus: version 8.1 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux For Real Time: version 7 only; version 8 only
  • Red Hat Enterprise Linux For Real Time For Nfv: version 7 only; version 8 only
  • Red Hat Enterprise Linux For Real Time For Nfv Tus: version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux For Real Time Tus: version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux For Scientific Computing: version 7.0 only
  • Red Hat Enterprise Linux Server: version 7.0 only
  • Red Hat Enterprise Linux Server Aus: version 7.6 only; version 7.7 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux Server For Power Little Endian Update Services For SAP Solutions: version 7.6 only; version 8.1 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux Server Tus: version 7.6 only; version 7.7 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux Server Update Services For SAP Solutions: version 7.6 only; version 7.7 only; version 8.1 only; version 8.2 only; version 8.4 only
  • Red Hat Enterprise Linux Workstation: version 7.0 only
  • Red Hat Openstack: version 13 only
  • Red Hat Software Collections: affected versions not specified
  • and 1 more

Published 2022-03-04. Last modified 2026-06-17.