Fixing Linux Server PwnKit Vulnerability CVE-2021-4034

Fixing Linux Server PwnKit Vulnerability CVE-2021-4034


2 min read

Cybersecurity is crucial in today's ever-evolving digital landscape, where cyber threats are constantly emerging. One such critical vulnerability that requires prompt attention is the PwnKit vulnerability, known as CVE-2021-4034.

This article will explore the nature of this vulnerability, its potential impact on Linux servers, and most importantly, the steps to effectively patch and secure your Linux server against this threat.

Understanding PwnKit Vulnerability CVE-2021-4034

The PwnKit vulnerability (CVE-2021-4034) is a critical security issue that affects Linux servers, particularly those running outdated kernel versions. This vulnerability allows malicious actors to execute arbitrary code on Linux systems and gain unauthorized access. Such unauthorized access can lead to data breaches and service disruptions.

Essential Precautions to Take

Regularly updating your Linux server with the latest security patches is the primary defense against potential threats. Ensuring that your system is up-to-date is a crucial step in closing known vulnerabilities and preventing cyber attackers from exploiting them.

If updating your kernel is problematic, a workaround is available. This involves tweaking the pkexec authorization setup in the SUID root program. SUID enables regular users to perform specific operations and access files with privileges typically reserved for the root user. By blocking malicious users from utilizing pkexec, you can eliminate this security vulnerability.

First, update your system:

sudo apt-get update sudo apt-get upgrade

On Arch Linux:

sudo pacman -Syu

On Fedora and RHEL:

sudo dnf upgrade

Next, alter user privileges to remove the SUID in pkexec by executing the following command:

sudo chmod 0755 /usr/bin/exec

This method offers a temporary solution. For robust protection, always keep your system updated.

Securing Servers Against Linux Kernel Vulnerabilities

One of the most effective ways to protect against known vulnerabilities is to keep your Linux kernel updated. Major Linux distributions release security patches and updates to fix identified vulnerabilities promptly. Regularly check for updates and apply them without delay.

Configuring a robust firewall and implementing access control mechanisms are also essential for minimizing the risk of unauthorized access and exploitation of core vulnerabilities. By diligently applying security updates and employing stringent access controls, you can significantly enhance your Linux kernel's security and protect your system from potential vulnerabilities.

Regularly monitoring security advisories and staying informed about the latest threats will help you take timely action to fortify your system's defenses against emerging risks.


In conclusion, safeguarding your Linux server against the PwnKit vulnerability CVE-2021-4034 is crucial to maintaining system security. By regularly updating your kernel, implementing a strong firewall, employing access control mechanisms, and staying informed about emerging threats, you can effectively protect your server from potential vulnerabilities and ensure a secure digital environment.