CVE-2021-24591 Explained : Impact and Mitigation

The Highlight WordPress plugin before version 0.9.3 is vulnerable to Authenticated Stored Cross-Site Scripting (XSS) attacks due to inadequate sanitization of its CustomCSS setting. This security flaw enables high privilege users to execute malicious scripts, bypassing the restrictions imposed by the unfiltered_html capability.

Understanding CVE-2021-24591

This section delves deeper into the details of the CVE-2021-24591 vulnerability in the Highlight WordPress plugin.

What is CVE-2021-24591?

The CVE-2021-24591 vulnerability refers to an Authenticated Stored Cross-Site Scripting (XSS) issue in the Highlight WordPress plugin versions prior to 0.9.3. It arises from the plugin's failure to properly sanitize the CustomCSS parameter, allowing attackers with high privileges to launch XSS attacks.

The Impact of CVE-2021-24591

The impact of CVE-2021-24591 is significant as it enables authenticated users with elevated privileges to inject malicious scripts into the plugin's CustomCSS setting. This could result in unauthorized access, data theft, or other malicious activities on the affected WordPress sites.

Technical Details of CVE-2021-24591

In this section, we explore the technical specifics of CVE-2021-24591 and how it affects systems and versions.

Vulnerability Description

The vulnerability stems from the Highlight plugin's failure to properly sanitize the CustomCSS parameter. This oversight allows attackers to insert and execute malicious scripts, posing a serious security risk to affected sites.

Affected Systems and Versions

The Highlight WordPress plugin versions prior to 0.9.3 are impacted by CVE-2021-24591. Websites using versions below this are vulnerable to the Authenticated Stored Cross-Site Scripting threat.

Exploitation Mechanism

Attackers can exploit this vulnerability by leveraging their high privileges to insert crafted scripts into the CustomCSS setting of the Highlight plugin. This malicious code can then be executed whenever the setting is rendered, potentially compromising the website.

Mitigation and Prevention

This section provides guidance on mitigating the risks posed by CVE-2021-24591 and securing WordPress installations.

Immediate Steps to Take

Website administrators are advised to update the Highlight plugin to version 0.9.3 or newer, which includes a patch for the Authenticated Stored Cross-Site Scripting vulnerability. Additionally, users should monitor their sites for any suspicious activities.

Long-Term Security Practices

To enhance security posture, follow security best practices such as regular security audits, restricting user privileges, and staying informed about plugin updates and vulnerabilities.

Patching and Updates

Regularly apply security patches and updates to all WordPress plugins and themes to protect against known vulnerabilities and ensure a secure website environment.