CVE-2021-26720 : What You Need to Know
Learn about CVE-2021-26720, a vulnerability in the Debian avahi package allowing local attackers to create a denial of service or arbitrary empty files. Understand the impact, technical details, and mitigation steps.
This article discusses CVE-2021-26720, a vulnerability in the Debian avahi package that can be exploited by a local attacker to create a denial of service or arbitrary empty files.
Understanding CVE-2021-26720
In this section, we will explore the details of the CVE-2021-26720 vulnerability.
What is CVE-2021-26720?
The vulnerability in avahi-daemon-check-dns.sh in the Debian avahi package through version 0.8-4 allows a local attacker to execute commands as root by exploiting a symlink attack on files under /run/avahi-daemon.
The Impact of CVE-2021-26720
CVE-2021-26720 can result in a denial of service or the creation of arbitrary empty files. It affects the Debian GNU/Linux packaging indirectly, impacting systems using SUSE.
Technical Details of CVE-2021-26720
In this section, we will delve into the technical aspects of the CVE-2021-26720 vulnerability.
Vulnerability Description
The vulnerability arises from the execution of avahi-daemon-check-dns.sh as root via /etc/network/if-up.d/avahi-daemon, enabling unauthorized actions by local attackers.
Affected Systems and Versions
The vulnerability affects the Debian avahi package through version 0.8-4, used in Debian GNU/Linux and indirectly in SUSE systems.
Exploitation Mechanism
Local attackers can exploit this vulnerability through a symlink attack on files under /run/avahi-daemon, allowing them to cause a denial of service or create arbitrary empty files.
Mitigation and Prevention
This section provides insights into mitigating and preventing exploitation of CVE-2021-26720.
Immediate Steps to Take
To mitigate the risk associated with CVE-2021-26720, users are advised to apply the latest security updates provided by Debian and SUSE.
Long-Term Security Practices
Implementing secure coding practices, restricting root access, and regularly monitoring system files can enhance security posture against similar vulnerabilities.
Patching and Updates
Regularly update the avahi package to the latest version and stay informed about security advisories to protect systems from potential exploitation.