CVE-2021-24604 : Exploit Details and Defense Strategies

This article provides details about CVE-2021-24604, a vulnerability in the Availability Calendar WordPress plugin before version 1.2.2 that could lead to authenticated stored Cross-Site Scripting attacks.

Understanding CVE-2021-24604

CVE-2021-24604 is a security vulnerability found in the Availability Calendar WordPress plugin that allows high privilege users to execute Cross-Site Scripting attacks.

What is CVE-2021-24604?

The vulnerability in the Availability Calendar plugin, before version 1.2.2, fails to properly sanitize or escape Category Names. This oversight enables high privilege users to conduct Cross-Site Scripting attacks, even when unfiltered_html is disabled.

The Impact of CVE-2021-24604

The impact of this vulnerability is significant as it exposes websites using the affected plugin to potential Cross-Site Scripting attacks. Attackers could inject malicious scripts into page/post content, posing a risk to site visitors and compromising site integrity.

Technical Details of CVE-2021-24604

The following technical details outline the specifics of CVE-2021-24604:

Vulnerability Description

The flaw in the Availability Calendar plugin allows attackers to execute Cross-Site Scripting attacks by manipulating Category Names without proper sanitization.

Affected Systems and Versions

Availability Calendar versions prior to 1.2.2 are vulnerable to this exploit.

Exploitation Mechanism

High privilege users can embed the associated shortcode in a page or post to execute malicious scripts through Category Names, regardless of unfiltered_html settings.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-24604, users and administrators can take the following steps:

Immediate Steps to Take

Update the Availability Calendar plugin to version 1.2.2 or higher to patch the vulnerability.

Long-Term Security Practices

Regularly monitor and apply security updates for all WordPress plugins and themes to prevent similar security incidents.

Patching and Updates

Stay informed about security best practices and new vulnerabilities that may affect WordPress installations.