CVE-2021-3656

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The issue 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.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.