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Linux Distros Unpatched Vulnerability : CVE-2021-43784

medium Nessus Plugin ID 224195

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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.

 - runc is a CLI tool for spawning and running containers on Linux according to the OCI specification. In runc, netlink is used internally as a serialization system for specifying the relevant container configuration to the `C` portion of the code (responsible for the based namespace setup of containers). In all versions of runc prior to 1.0.3, the encoder did not handle the possibility of an integer overflow in the 16-bit length field for the byte array attribute type, meaning that a large enough malicious byte array attribute could result in the length overflowing and the attribute contents being parsed as netlink messages for container configuration. This vulnerability requires the attacker to have some control over the configuration of the container and would allow the attacker to bypass the namespace restrictions of the container by simply adding their own netlink payload which disables all namespaces. The main users impacted are those who allow untrusted images with untrusted configurations to run on their machines (such as with shared cloud infrastructure). runc version 1.0.3 contains a fix for this bug. As a workaround, one may try disallowing untrusted namespace paths from your container. It should be noted that untrusted namespace paths would allow the attacker to disable namespace protections entirely even in the absence of this bug. (CVE-2021-43784)

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-2021-43784

https://ubuntu.com/security/CVE-2021-43784

Plugin Details

Severity: Medium

ID: 224195

File Name: unpatched_CVE_2021_43784.nasl

Version: 1.3

Type: local

Agent: unix

Family: Misc.

Published: 3/5/2025

Updated: 9/2/2025

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

Risk Information

VPR

Risk Factor: Medium

Score: 4.2

CVSS v2

Risk Factor: Medium

Base Score: 6

Temporal Score: 4.7

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

CVSS Score Source: CVE-2021-43784

CVSS v3

Risk Factor: Medium

Base Score: 5

Temporal Score: 4.5

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

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

Vulnerability Information

CPE: cpe:/o:centos:centos:8, p-cpe:/a:centos:centos:runc, cpe:/o:redhat:enterprise_linux:8, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:redhat:enterprise_linux:runc, p-cpe:/a:canonical:ubuntu_linux:runc

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

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 12/6/2021

Reference Information

CVE: CVE-2021-43784