WaratekVRT Sign in

CVE-2021-3656

Affected software2 products, listed below
Severity8.8 High CVSS 3.1 2 scores
WeaknessMissing authorization (CWE-862)
Published4 Mar 2022
Updated17 Jun 2026

Description

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.

Exploitation status

No public exploit

No exploit has been reported in the sources we check. The 1 repository below are public GitHub repositories with fewer than 5 stars.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment no assessment published
  • Indexed PoC 1 indexed, none at 5+ stars
  • EPSS 0.66% chance in 30 days

1 of these are GitHub repositories with fewer than 5 stars. They are listed for reference and don't count toward the exploitation status above.

IndexArtifactStarsFirst seen
GitHub PoC rami08448/CVE-2021-3656-Demo 2 2022-11-05

Waratek protection

Outside Waratek scope

A Java vulnerability, but not one Waratek protects. It affects only Java on a user's desktop (applets, Web Start, JavaFX, the installer), sits in a product the Waratek agent can't be installed into, or is in a package we don't expect in business applications. The decision below says which.

  • Protection none
  • Action not pursued none
  • Review human Researcher
  • Record active
Decided by Manual classification of this CVE in the legacy dataset
Finding A manual classification set this CVE's status to Outside Waratek scope, but the CVE names a tracked product.

CVSS

8.8 HIGH v3.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H 2 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 3.1 8.8 HIGH CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H NVD Primary published
CVSS 2.0 7.2 none AV:L/AC:L/Au:N/C:C/I:C/A:C NVD Primary

Affected software and releases

Products and versions

26 products, 63 version entries
SourceVendorProductSchemeAffected versions
nvd fedoraproject fedora generic 33 · 34
nvd linux linux kernel generic ≥ 4.13 and < 4.14.245 · ≥ 4.15 and < 4.19.205 · ≥ 4.20 and < 5.4.142 · ≥ 5.5 and < 5.10.60 · ≥ 5.11 and < 5.13.12 · 5.14 · 5.14:rc1 · 5.14:rc2 · 5.14:rc3 · 5.14:rc4 · 5.14:rc5 · 5.14:rc6
nvd redhat 3scale api management generic 2.0
nvd redhat codeready linux builder generic any version
nvd redhat enterprise linux generic 8.0
nvd redhat enterprise linux desktop generic 7.0
nvd redhat enterprise linux eus generic 8.1 · 8.2 · 8.4
nvd redhat enterprise linux for ibm z systems generic 7.0 · 8.0
nvd redhat enterprise linux for ibm z systems eus generic 8.1 · 8.2 · 8.4
nvd redhat enterprise linux for power big endian generic 7.0
nvd redhat enterprise linux for power little endian generic 7.0 · 8.0
nvd redhat enterprise linux for power little endian eus generic 8.1 · 8.2 · 8.4
nvd redhat enterprise linux for real time generic 7 · 8
nvd redhat enterprise linux for real time for nfv generic 7 · 8
nvd redhat enterprise linux for real time for nfv tus generic 8.2 · 8.4
nvd redhat enterprise linux for real time tus generic 8.2 · 8.4
nvd redhat enterprise linux for scientific computing generic 7.0
nvd redhat enterprise linux server generic 7.0
nvd redhat enterprise linux server aus generic 7.6 · 7.7 · 8.2 · 8.4
nvd redhat enterprise linux server for power little endian update services for sap solutions generic 7.6 · 8.1 · 8.2 · 8.4
nvd redhat enterprise linux server tus generic 7.6 · 7.7 · 8.2 · 8.4
nvd redhat enterprise linux server update services for sap solutions generic 7.6 · 7.7 · 8.1 · 8.2 · 8.4
nvd redhat enterprise linux workstation generic 7.0
nvd redhat openstack generic 13
nvd redhat software collections generic any version
nvd redhat virtualization host generic 4.0

References

URLTags
https://bugzilla.redhat.com/show_bug.cgi?id=1983988 Issue Tracking, Third Party Advisory
https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?id=c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc Patch, Third Party Advisory
https://github.com/torvalds/linux/commit/c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc Patch, Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/08/16/1 Mailing List, Third Party Advisory

Timeline

Published2022-03-04By the CVE Program.
NVD record modified2026-06-17NVD's own last-modified date for this record.