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CVE-2021-3653

Public on 2021-09-08
Modified on 2021-09-15
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.

Severity
Medium
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CVSS v3 Base Score
8.8
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Affected Packages

Platform Package Release Date Advisory
Amazon Linux 2 - Core kernel 2021-09-08 23:35 ALAS2-2021-1704
Amazon Linux 2 - Kernel-5.10 Extra kernel 2022-01-20 23:50 ALAS2KERNEL-5.10-2022-005
Amazon Linux 2 - Microvm-kernel-4.14 Extra microvm-kernel 2023-09-14 04:27 ALAS2MICROVM-KERNEL-4.14-2023-002
Amazon Linux 2 - Microvm-kernel-4.14 Extra microvm-kernel 2023-09-14 04:27 ALAS2MICROVM-KERNEL-4.14-2023-003

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD CVSSv2 6.1 AV:L/AC:L/Au:N/C:P/I:P/A:C
NVD CVSSv3 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References

Red Hat: CVE-2021-3653 Mitre: CVE-2021-3653 FAQs regarding Amazon Linux ALAS/CVE Severity