{"id":"CVE-2021-3656","details":"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.","modified":"2026-04-11T16:26:00.972518Z","published":"2022-03-04T19:15:08.677Z","related":["ALSA-2021:4056","MGASA-2021-0409","MGASA-2021-0410","SUSE-SU-2021:3073-1","SUSE-SU-2021:3177-1","SUSE-SU-2021:3178-1","SUSE-SU-2021:3179-1","SUSE-SU-2021:3192-1","SUSE-SU-2021:3205-1","SUSE-SU-2021:3205-2","SUSE-SU-2021:3206-1","SUSE-SU-2021:3207-1","SUSE-SU-2021:3217-1","SUSE-SU-2021:3415-1","SUSE-SU-2021:3876-1","SUSE-SU-2021:3969-1","SUSE-SU-2021:3972-1","openSUSE-SU-2021:1271-1","openSUSE-SU-2021:3179-1","openSUSE-SU-2021:3205-1","openSUSE-SU-2021:3876-1","openSUSE-SU-2024:10728-1","openSUSE-SU-2024:13704-1"],"references":[{"type":"ADVISORY","url":"https://www.openwall.com/lists/oss-security/2021/08/16/1"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1983988"},{"type":"FIX","url":"https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?id=c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc"},{"type":"FIX","url":"https://github.com/torvalds/linux/commit/c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/torvalds/linux","events":[{"introduced":"0"},{"last_affected":"7d2a07b769330c34b4deabeed939325c77a7ec2f"},{"introduced":"0"},{"last_affected":"e73f0f0ee7541171d89f2e2491130c7771ba58d3"},{"introduced":"0"},{"last_affected":"2734d6c1b1a089fb593ef6a23d4b70903526fe0c"},{"introduced":"0"},{"last_affected":"ff1176468d368232b684f75e82563369208bc371"},{"introduced":"0"},{"last_affected":"c500bee1c5b2f1d59b1081ac879d73268ab0ff17"},{"introduced":"0"},{"last_affected":"36a21d51725af2ce0700c6ebcb6b9594aac658a6"},{"introduced":"0"},{"last_affected":"7c60610d476766e128cc4284bb6349732cbd6606"},{"introduced":"0"},{"last_affected":"39a8804455fb23f09157341d3ba7db6d7ae6ee76"},{"fixed":"c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc"}],"database_specific":{"versions":[{"introduced":"0"},{"last_affected":"5.14-NA"},{"introduced":"0"},{"last_affected":"5.14-rc1"},{"introduced":"0"},{"last_affected":"5.14-rc2"},{"introduced":"0"},{"last_affected":"5.14-rc3"},{"introduced":"0"},{"last_affected":"5.14-rc4"},{"introduced":"0"},{"last_affected":"5.14-rc5"},{"introduced":"0"},{"last_affected":"5.14-rc6"},{"introduced":"0"},{"last_affected":"4.0"}]}}],"versions":["v2.6.12-rc2","v2.6.12-rc3","v2.6.12-rc4","v2.6.13","v2.6.13-rc1","v2.6.13-rc2","v2.6.13-rc3","v2.6.13-rc4","v2.6.13-rc5","v2.6.13-rc6","v2.6.13-rc7","v2.6.14-rc1","v2.6.14-rc2","v2.6.14-rc3","v2.6.15-rc1","v2.6.15-rc2","v2.6.15-rc4","v2.6.15-rc5","v2.6.15-rc7","v2.6.16","v2.6.16-rc1","v2.6.16-rc2","v2.6.16-rc3","v2.6.16-rc4","v2.6.16-rc5","v2.6.16-rc6","v2.6.17","v2.6.17-rc1","v2.6.17-rc2","v2.6.17-rc3","v2.6.17-rc4","v2.6.17-rc5","v2.6.17-rc6","v2.6.18","v2.6.18-rc1","v2.6.18-rc2","v2.6.18-rc3","v2.6.18-rc5","v2.6.18-rc6","v2.6.19-rc1","v2.6.19-rc2","v2.6.20-rc1","v2.6.20-rc2","v2.6.20-rc3","v2.6.20-rc4","v2.6.20-rc5","v2.6.20-rc6","v2.6.20-rc7","v2.6.21","v2.6.21-rc1","v2.6.21-rc2","v2.6.21-rc3","v2.6.21-rc4","v2.6.21-rc5","v2.6.21-rc6","v2.6.21-rc7","v2.6.22","v2.6.22-rc1","v2.6.22-rc2","v2.6.22-rc3","v2.6.22-rc4","v2.6.22-rc5","v2.6.22-rc6","v2.6.22-rc7","v2.6.23","v2.6.23-rc1","v2.6.23-rc2","v2.6.23-rc3","v2.6.23-rc4","v2.6.23-rc5","v2.6.23-rc6","v2.6.23-rc7","v2.6.23-rc8","v2.6.23-rc9","v2.6.24","v2.6.24-rc1","v2.6.24-rc2","v2.6.24-rc3","v2.6.24-rc4","v2.6.24-rc5","v2.6.24-rc6","v2.6.24-rc7","v2.6.24-rc8","v2.6.25","v2.6.25-rc1","v2.6.25-rc2","v2.6.25-rc3","v2.6.25-rc4","v2.6.25-rc5","v2.6.25-rc6","v2.6.25-rc7","v2.6.25-rc8","v2.6.25-rc9","v2.6.26","v2.6.26-rc1","v2.6.26-rc2","v2.6.26-rc3","v2.6.26-rc4","v2.6.26-rc5","v2.6.26-rc6","v2.6.26-rc7","v2.6.26-rc8","v2.6.26-rc9","v2.6.27","v2.6.27-rc1","v2.6.27-rc2","v2.6.27-rc3","v2.6.27-rc4","v2.6.27-rc5","v2.6.27-rc6","v2.6.27-rc7","v2.6.27-rc8","v2.6.27-rc9","v2.6.28","v2.6.28-rc1","v2.6.28-rc2","v2.6.28-rc3","v2.6.28-rc4","v2.6.28-rc5","v2.6.28-rc6","v2.6.28-rc7","v2.6.28-rc8","v2.6.28-rc9","v2.6.29","v2.6.29-rc1","v2.6.29-rc2","v2.6.29-rc3","v2.6.29-rc4","v2.6.29-rc5","v2.6.29-rc6","v2.6.29-rc7","v2.6.29-rc8","v2.6.30","v2.6.30-rc1","v2.6.30-rc2","v2.6.30-rc3","v2.6.30-rc4","v2.6.30-rc5","v2.6.30-rc6","v2.6.30-rc7","v2.6.30-rc8","v2.6.31","v2.6.31-rc1","v2.6.31-rc2","v2.6.31-rc3","v2.6.31-rc4","v2.6.31-rc5","v2.6.31-rc6","v2.6.31-rc7","v2.6.31-rc8","v2.6.31-rc9","v2.6.32","v2.6.32-rc1","v2.6.32-rc2","v2.6.32-rc3","v2.6.32-rc4","v2.6.32-rc5","v2.6.32-rc6","v2.6.32-rc7","v2.6.32-rc8","v2.6.33","v2.6.33-rc1","v2.6.33-rc2","v2.6.33-rc3","v2.6.33-rc4","v2.6.33-rc5","v2.6.33-rc6","v2.6.33-rc7","v2.6.33-rc8","v2.6.34","v2.6.34-rc1","v2.6.34-rc2","v2.6.34-rc3","v2.6.34-rc4","v2.6.34-rc5","v2.6.34-rc6","v2.6.34-rc7","v2.6.35","v2.6.35-rc1","v2.6.35-rc2","v2.6.35-rc3","v2.6.35-rc4","v2.6.35-rc5","v2.6.35-rc6","v2.6.36","v2.6.36-rc1","v2.6.36-rc2","v2.6.36-rc3","v2.6.36-rc4","v2.6.36-rc5","v2.6.36-rc6","v2.6.36-rc7","v2.6.36-rc8","v2.6.37","v2.6.37-rc1","v2.6.37-rc2","v2.6.37-rc3","v2.6.37-rc4","v2.6.37-rc5","v2.6.37-rc6","v2.6.37-rc7","v2.6.37-rc8","v2.6.38","v2.6.38-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