CVE Feed

    Dashboard / CVE / CVE-2021-3656

    CVE-2021-3656

    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.

    Published:Aug 16, 2021
    Last Modified:Nov 21, 2024
    EPS:Mar 4, 2022
    EPSS Score:0.00057
    CVSS Score:8.8

    Affected Products

    Vendor
    Fedoraproject
    Product
    Fedora
    Vendor
    Linux
    Product
    Linux Kernel
    Vendor
    Redhat
    Product
    3scale Api Management
    Vendor
    Redhat
    Product
    Codeready Linux Builder
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Redhat
    Product
    Enterprise Linux Desktop
    Vendor
    Redhat
    Product
    Enterprise Linux Eus
    Vendor
    Redhat
    Product
    Enterprise Linux For Ibm Z Systems
    Vendor
    Redhat
    Product
    Enterprise Linux For Ibm Z Systems Eus
    Vendor
    Redhat
    Product
    Enterprise Linux For Power Big Endian
    Vendor
    Redhat
    Product
    Enterprise Linux For Power Little Endian
    Vendor
    Redhat
    Product
    Enterprise Linux For Power Little Endian Eus
    Vendor
    Redhat
    Product
    Enterprise Linux For Real Time
    Vendor
    Redhat
    Product
    Enterprise Linux For Real Time For Nfv
    Vendor
    Redhat
    Product
    Enterprise Linux For Real Time For Nfv Tus
    Vendor
    Redhat
    Product
    Enterprise Linux For Real Time Tus
    Vendor
    Redhat
    Product
    Enterprise Linux For Scientific Computing
    Vendor
    Redhat
    Product
    Enterprise Linux Server
    Vendor
    Redhat
    Product
    Enterprise Linux Server Aus
    Vendor
    Redhat
    Product
    Enterprise Linux Server For Power Little Endian Update Services For Sap Solutions
    Vendor
    Redhat
    Product
    Enterprise Linux Server Tus
    Vendor
    Redhat
    Product
    Enterprise Linux Server Update Services For Sap Solutions
    Vendor
    Redhat
    Product
    Enterprise Linux Workstation
    Vendor
    Redhat
    Product
    Openstack
    Vendor
    Redhat
    Product
    Rhel Aus
    Vendor
    Redhat
    Product
    Rhel E4s
    Vendor
    Redhat
    Product
    Rhel Eus
    Vendor
    Redhat
    Product
    Rhel Extras Rt
    Vendor
    Redhat
    Product
    Rhel Tus
    Vendor
    Redhat
    Product
    Software Collections
    Vendor
    Redhat
    Product
    Virtualization Host

    Exploits

    https://github.com/rami08448/CVE-2021-3656-Demo

    Common Weakness Enumeration

    CWE-862 Missing Authorization

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-665 Exploitation of Thunderbolt Protection Flaws

    Related CVEs

    CVE-2026-54231 (CVSS 5.5) — A content injection vulnerability was found in the ABRT post-create event handler scripts in libreport. The ev…
    CVE-2026-54230 (CVSS 7) — A symlink following vulnerability was found in the ABRT post-create event handler scripts in libreport. Event …
    CVE-2026-35094 (CVSS 3.3) — A flaw was found in libinput. An attacker capable of deploying a Lua plugin file in specific system directorie…
    CVE-2026-35093 (CVSS 8.8) — A flaw was found in libinput. A local attacker who can place a specially crafted Lua bytecode file in certain …
    CVE-2024-3056 (CVSS 7.7) — A flaw was found in Podman. This issue may allow an attacker to create a specially crafted container that, whe…
    CVE-2024-6293 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-6292 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-6291 (CVSS 8.8) — Use after free in Swiftshader in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentiall…
    CVE-2024-6290 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-38277 (CVSS 5.4) — A unique key should be generated for a user's QR login key and their auto-login key, so the same key cannot be…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High