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Linux Distros Unpatched Vulnerability : CVE-2020-8834

medium Nessus Plugin ID 223612

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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.

 - KVM in the Linux kernel on Power8 processors has a conflicting use of HSTATE_HOST_R1 to store r1 state in kvmppc_hv_entry plus in kvmppc_{save,restore}_tm, leading to a stack corruption. Because of this, an attacker with the ability run code in kernel space of a guest VM can cause the host kernel to panic. There were two commits that, according to the reporter, introduced the vulnerability: f024ee098476 (KVM: PPC:
 Book3S HV: Pull out TM state save/restore into separate procedures) 87a11bb6a7f7 (KVM: PPC: Book3S HV:
 Work around XER[SO] bug in fake suspend mode) The former landed in 4.8, the latter in 4.17. This was fixed without realizing the impact in 4.18 with the following three commits, though it's believed the first is the only strictly necessary commit: 6f597c6b63b6 (KVM: PPC: Book3S PR: Add guest MSR parameter for kvmppc_save_tm()/kvmppc_restore_tm()) 7b0e827c6970 (KVM: PPC: Book3S HV: Factor fake-suspend handling out of kvmppc_save/restore_tm) 009c872a8bc4 (KVM: PPC: Book3S PR: Move kvmppc_save_tm/kvmppc_restore_tm to separate file) (CVE-2020-8834)

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

Solution

There is no known solution at this time.

Plugin Details

Severity: Medium

ID: 223612

File Name: unpatched_CVE_2020_8834.nasl

Version: 1.1

Type: local

Agent: unix

Family: Misc.

Published: 3/4/2025

Updated: 3/4/2025

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Medium

Base Score: 4.9

Temporal Score: 3.8

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

CVSS Score Source: CVE-2020-8834

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.9

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

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

Vulnerability Information

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

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 4/6/2020

Reference Information

CVE: CVE-2020-8834