#VU56904 Security restrictions bypass in Linux kernel - CVE-2021-3653

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Main Vulnerability Database Vulnerabilities #VU56904

#VU56904 Security restrictions bypass in Linux kernel - CVE-2021-3653

Published: September 28, 2021


Vulnerability identifier: #VU56904
Vulnerability risk: Low
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2021-3653
CWE-ID: CWE-264
Exploitation vector: Remote access
Exploit availability: No public exploit available
Vulnerable software:
Linux kernel
Software vendor:
Linux Foundation

Description

The vulnerability allows a malicious guest to escalate privileges on the system.

The vulnerability exists due to improperly imposed security restrictions within 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.


Remediation

Install updates from vendor's website.

External links