CVE-2021-3656

HIGH

Linux Kernel < 4.14.245 - Missing Authorization

Title source: rule
STIX 2.1

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.

Exploits (1)

nomisec WRITEUP 2 stars
by rami08448 · poc
https://github.com/rami08448/CVE-2021-3656-Demo

References (4)

Core 4
Core References
Mailing List, Third Party Advisory x_refsource_misc
https://www.openwall.com/lists/oss-security/2021/08/16/1
Issue Tracking, Third Party Advisory x_refsource_misc
https://bugzilla.redhat.com/show_bug.cgi?id=1983988

Scores

CVSS v3 8.8
EPSS 0.0007
EPSS Percentile 20.3%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Details

CWE
CWE-862
Status published
Products (44)
fedoraproject/fedora 33
fedoraproject/fedora 34
linux/linux_kernel 5.14 (7 CPE variants)
linux/linux_kernel 4.13 - 4.14.245
redhat/3scale_api_management 2.0
redhat/codeready_linux_builder
redhat/enterprise_linux 8.0
redhat/enterprise_linux_desktop 7.0
redhat/enterprise_linux_eus 8.1
redhat/enterprise_linux_eus 8.2
... and 34 more
Published Mar 04, 2022
Tracked Since Feb 18, 2026