Detections
Analytics

Linux Distros Unpatched Vulnerability : CVE-2021-29657

high Nessus Plugin ID 223718

Language:

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

 - arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.
 (CVE-2021-29657)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

See Also

https://access.redhat.com/security/cve/cve-2021-29657

https://ubuntu.com/security/CVE-2021-29657

Plugin Details

Severity: High

ID: 223718

File Name: unpatched_CVE_2021_29657.nasl

Version: 1.2

Type: local

Agent: unix

Family: Misc.

Published: 3/4/2025

Updated: 8/11/2025

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 6.9

Temporal Score: 5.4

Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2021-29657

CVSS v3

Risk Factor: High

Base Score: 7.4

Temporal Score: 6.7

Vector: CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:redhat:enterprise_linux:kernel-rt-selftests-internal, p-cpe:/a:centos:centos:kernel-rt-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, cpe:/o:centos:centos:8, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:centos:centos:kernel-rt-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:centos:centos:kernel-rt-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug, p-cpe:/a:redhat:enterprise_linux:kernel-rt-core, p-cpe:/a:centos:centos:kernel-rt-debug-kvm, p-cpe:/a:centos:centos:kernel-rt-debug-devel, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:redhat:enterprise_linux:kernel-rt, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:centos:centos:kernel-rt-core, p-cpe:/a:centos:centos:kernel-rt-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:centos:centos:kernel-rt-debug, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:centos:centos:kernel-rt-modules, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-extra, p-cpe:/a:centos:centos:kernel-rt-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:centos:centos:kernel-rt-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:centos:centos:kernel-rt-debug-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-core, p-cpe:/a:centos:centos:kernel-rt-debug-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-edge, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:centos:centos:kernel-rt-debug-core, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:centos:centos:kernel-rt

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 7/22/2021

Reference Information

CVE: CVE-2021-29657