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Linux Distros Unpatched Vulnerability : CVE-2021-20233

high Nessus Plugin ID 223657

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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.

 - A flaw was found in grub2 in versions prior to 2.06. Setparam_prefix() in the menu rendering code performs a length calculation on the assumption that expressing a quoted single quote will require 3 characters, while it actually requires 4 characters which allows an attacker to corrupt memory by one byte for each quote in the input. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability. (CVE-2021-20233)

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-2021-20233

https://ubuntu.com/security/CVE-2021-20233

Plugin Details

Severity: High

ID: 223657

File Name: unpatched_CVE_2021_20233.nasl

Version: 1.4

Type: local

Agent: unix

Family: Misc.

Published: 3/4/2025

Updated: 9/3/2025

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

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.3

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

CVSS Score Source: CVE-2021-20233

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:14.04:-:lts, cpe:/o:centos:centos:7, p-cpe:/a:centos:centos:fwupdate, p-cpe:/a:centos:centos:fwupdate-efi, cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:centos:centos:fwupdate-libs, p-cpe:/a:redhat:enterprise_linux:fwupd, p-cpe:/a:redhat:enterprise_linux:fwupd-devel, p-cpe:/a:redhat:enterprise_linux:fwupdate, p-cpe:/a:centos:centos:fwupd, p-cpe:/a:redhat:enterprise_linux:fwupdate-libs, p-cpe:/a:centos:centos:fwupd-devel, p-cpe:/a:redhat:enterprise_linux:fwupdate-efi, p-cpe:/a:centos:centos:fwupdate-devel, p-cpe:/a:canonical:ubuntu_linux:grub2-signed, p-cpe:/a:redhat:enterprise_linux:fwupdate-devel

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

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 7/30/2020

Reference Information

CVE: CVE-2021-20233