Seven PHPmailer Vulnerabilities Addressed in Ubuntu

Rohan Timalsina

March 13, 2024 - TuxCare expert team

In the realm of web development, it is critical to make sure our applications are secure. Recently, the Ubuntu security team addressed a number of vulnerabilities in PHPMailer, a widely used email transfer class for PHP. These vulnerabilities could potentially open the door to malicious attacks, including cross-site scripting (XSS) and the execution of arbitrary code. Let’s delve into the details of these vulnerabilities and the measures taken to address them.

PHPmailer Vulnerabilities Overview

CVE-2016-10033, CVE-2016-10045

Dawid Golunski discovered that PHPMailer was susceptible to arbitrary code execution due to improper handling of user input data used as arguments to functions executed by the system shell. Although this issue exclusively affected Ubuntu 16.04 ESM, its potential impact was significant.

CVE-2017-11503

This vulnerability, identified by an oversight in escaping characters in specific fields of the code_generator.php example code, paved the way for cross-site scripting (XSS) attacks. This issue was only fixed in Ubuntu 16.04 and Ubuntu 18.04.

CVE-2017-5223

Yongxiang Li’s discovery highlighted PHPMailer’s failure to appropriately convert relative paths provided as user input when attaching files to messages. Exploiting this flaw could lead to unauthorized access and exposure of sensitive information, exclusively impacting Ubuntu 16.04 ESM.

CVE-2018-19296

Sehun Oh’s finding pointed out PHPMailer’s inadequacy in processing untrusted non-local file attachments, potentially leading to object injection and subsequent arbitrary code execution. Again, this PHPmailer vulnerability only affected Ubuntu 16.04 and could be used to execute arbitrary code.

CVE-2020-13625

Elar Lang’s discovery underscored PHPMailer’s oversight in escaping file attachment names, posing a risk of misinterpretation by entities processing the message. This issue, affecting Ubuntu 16.04 and Ubuntu 20.04, highlighted the importance of stringent attachment handling protocols.

CVE-2021-3603

The last vulnerability, brought to light by an oversight in PHPMailer’s handling of callables in its validateAddress function, raised concerns about potential execution of untrusted code. This issue, addressed in Ubuntu 20.04 and Ubuntu 22.04, highlighted the evolving nature of security threats.

Mitigation Efforts

Upon the discovery of these PHPmailer vulnerabilities, the Ubuntu security team swiftly responded by releasing security updates. These updates were targeted at Ubuntu 22.04 LTS, Ubuntu 20.04 LTS, Ubuntu 18.04 ESM, and Ubuntu 16.04 ESM releases, ensuring that users could promptly patch their systems and mitigate the associated risks. While vulnerabilities in Linux may surface, proactive measures, such as timely patching are crucial in protecting our digital ecosystems against potential threats.

Security updates for Ubuntu 16.04 and Ubuntu 18.04 are only available with Ubuntu Pro. Alternatively, you can utilize TuxCare’s Extended Lifecycle Support to receive vendor-grade security patches and safeguard your end-of-life Ubuntu systems. Learn how Extended Lifecycle Support maintains security and compliance of end-of-life Linux operating systems.

Source: USN-5956-1

Summary