CVE-2021-3653 Information

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.

CVSS Vector

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

Reference

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

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

8.8