CVE-2021-3653

high

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 "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. This flaw affects Linux kernel versions prior to 5.14-rc7.

References

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

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

https://lists.debian.org/debian-lts-announce/2021/10/msg00010.html

https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html

http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html

Details

Source: MITRE

Published: 2021-09-29

Updated: 2022-03-31

Type: CWE-862

Risk Information

CVSS v2

Base Score: 6.1

Vector: AV:L/AC:L/Au:N/C:P/I:P/A:C

Impact Score: 8.5

Exploitability Score: 3.9

Severity: MEDIUM

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Impact Score: 6

Exploitability Score: 2

Severity: HIGH