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Linux Distros Unpatched Vulnerability : CVE-2021-4203

medium Nessus Plugin ID 244041

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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 use-after-free read flaw was found in sock_getsockopt() in net/core/sock.c due to SO_PEERCRED and SO_PEERGROUPS race with listen() (and connect()) in the Linux kernel. In this flaw, an attacker with a user privileges may crash the system or leak internal kernel information. (CVE-2021-4203)

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-2021-4203

https://ubuntu.com/security/CVE-2021-4203

Plugin Details

Severity: Medium

ID: 244041

File Name: unpatched_CVE_2021_4203.nasl

Version: 1.7

Type: local

Agent: unix

Family: Misc.

Published: 8/6/2025

Updated: 2/18/2026

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: Medium

Base Score: 4.9

Temporal Score: 4.4

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

CVSS Score Source: CVE-2021-4203

CVSS v3

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 6.4

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:redhat:enterprise_linux:6, p-cpe:/a:redhat:enterprise_linux:kernel-doc, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:centos:centos:kernel-debug-devel, p-cpe:/a:centos:centos:kernel-kdump-devel, p-cpe:/a:centos:centos:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, p-cpe:/a:centos:centos:kernel-rt-doc, p-cpe:/a:redhat:enterprise_linux:kernel, p-cpe:/a:centos:centos:kernel-kdump, cpe:/o:canonical:ubuntu_linux:14.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:redhat:enterprise_linux:kernel-firmware, p-cpe:/a:centos:centos:python-perf, p-cpe:/a:centos:centos:kernel-rt-devel, p-cpe:/a:centos:centos:kernel-bootwrapper, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace-devel, p-cpe:/a:redhat:enterprise_linux:kernel-bootwrapper, p-cpe:/a:canonical:ubuntu_linux:linux-realtime, p-cpe:/a:redhat:enterprise_linux:python-perf, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:redhat:enterprise_linux:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs-devel, p-cpe:/a:centos:centos:kernel-rt-trace-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-rt-doc, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs, p-cpe:/a:redhat:enterprise_linux:perf, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:centos:centos:kernel-headers, p-cpe:/a:redhat:enterprise_linux:bpftool, p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-tools, p-cpe:/a:centos:centos:kernel-tools-libs-devel, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:centos:centos:kernel-rt-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:centos:centos:kernel-rt, p-cpe:/a:centos:centos:kernel-tools, p-cpe:/a:redhat:enterprise_linux:kernel-kdump, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:centos:centos:kernel-rt-trace, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:centos:centos:kernel-rt-debug, p-cpe:/a:centos:centos:kernel-firmware, p-cpe:/a:centos:centos:kernel-doc, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:centos:centos:kernel-tools-libs, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.6, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:centos:centos:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace, p-cpe:/a:redhat:enterprise_linux:kernel-headers, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.8, cpe:/o:centos:centos:7, p-cpe:/a:canonical:ubuntu_linux:linux-raspi-realtime, p-cpe:/a:centos:centos:kernel-debug, p-cpe:/a:canonical:ubuntu_linux:linux-intel-iot-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, p-cpe:/a:canonical:ubuntu_linux:linux, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-rt, p-cpe:/a:canonical:ubuntu_linux:linux-intel-5.13, p-cpe:/a:centos:centos:perf, p-cpe:/a:centos:centos:kernel-rt-debug-kvm, p-cpe:/a:centos:centos:bpftool, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:centos:centos:kernel-rt-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-kdump-devel, p-cpe:/a:redhat:enterprise_linux:kernel-debug, p-cpe:/a:centos:centos:kernel, p-cpe:/a:centos:centos:kernel-rt-trace-devel, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug

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

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 11/4/2021

Reference Information

CVE: CVE-2021-4203