Rapid7 Vulnerability & Exploit Database

Red Hat: CVE-2021-3656: CVE-2021-3656 kernel: SVM nested virtualization issue in KVM (VMLOAD/VMSAVE) (Multiple Advisories)

Free InsightVM Trial No Credit Card Necessary
Watch Demo See how it all works
Back to Search

Red Hat: CVE-2021-3656: CVE-2021-3656 kernel: SVM nested virtualization issue in KVM (VMLOAD/VMSAVE) (Multiple Advisories)

Severity
7
CVSS
(AV:L/AC:L/Au:N/C:C/I:C/A:C)
Published
09/28/2021
Created
09/30/2021
Added
09/29/2021
Modified
03/13/2024

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.

Solution(s)

  • redhat-upgrade-kernel
  • redhat-upgrade-kernel-rt

References

  • CVE-2021-3656
  • RHSA-2021:3676
  • RHSA-2021:3801
  • RHSA-2021:3802
  • RHSA-2021:3904
  • RHSA-2021:3909
  • RHSA-2021:4056
  • RHSA-2021:4088
View more

insightVM

Advanced vulnerability management analytics and reporting.
Key Features
Free InsightVM Trial View All Features

With Rapid7 live dashboards, I have a clear view of all the assets on my network, which ones can be exploited, and what I need to do in order to reduce the risk in my environment in real-time. No other tool gives us that kind of value and insight.

– Scott Cheney, Manager of Information Security, Sierra View Medical Center

;