CVE-2024-13323 in Booking Calendar
Summary
by MITRE • 01/14/2025
The WP Booking Calendar plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'booking' shortcode in all versions up to, and including, 10.9.2 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 08/13/2025
The WP Booking Calendar plugin represents a widely used solution for managing reservations and bookings within WordPress environments, serving thousands of websites globally. This particular vulnerability exists within the plugin's 'booking' shortcode functionality, which allows administrators to embed booking forms and calendars directly into WordPress pages and posts. The vulnerability affects all versions up to and including 10.9.2, making it a persistent threat across a significant portion of the plugin's user base. The issue manifests as a stored cross-site scripting vulnerability that can be exploited by attackers who have already gained contributor-level access or higher within the WordPress environment.
The technical flaw stems from inadequate input sanitization and output escaping mechanisms within the plugin's codebase. When users supply attributes to the booking shortcode, the plugin fails to properly validate or sanitize these inputs before processing them. This insufficient sanitization creates a pathway for malicious actors to inject malicious scripts that are then stored within the plugin's data structures. The vulnerability is classified as stored XSS because the malicious code is persisted in the database and executed whenever affected pages are accessed by other users. The root cause aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities due to insufficient input validation and output escaping.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with significant privileges within the compromised environment. With contributor-level access or higher, attackers can inject scripts that could steal user sessions, redirect visitors to malicious sites, or even modify content on the affected website. The stored nature of the vulnerability means that once injected, the malicious code remains active until manually removed, potentially affecting all users who access the compromised pages. This creates a persistent threat that could be leveraged for extended periods without detection, particularly in environments where content is frequently updated or where multiple contributors maintain the site.
The exploitation of this vulnerability follows established patterns from ATT&CK framework's T1566.001 technique, which involves social engineering through malicious web content. Attackers typically need to gain access to a contributor account or higher, which can be achieved through various means including credential theft, phishing, or exploiting other vulnerabilities within the WordPress environment. Once inside, they can navigate to pages containing the booking shortcode, inject malicious scripts, and wait for other users to access those pages. The vulnerability essentially transforms the legitimate booking functionality into a weapon for executing malicious code, making it particularly dangerous in multi-user environments where different privilege levels exist. Organizations should implement comprehensive monitoring of user activities and content changes to detect unauthorized injections, while also ensuring all users maintain strong authentication practices.
Mitigation strategies should focus on immediate patching of the vulnerable plugin versions, with administrators upgrading to versions that contain proper input sanitization and output escaping mechanisms. Security measures including regular security audits, user access reviews, and implementation of content security policies can help reduce the attack surface. Additionally, monitoring for unauthorized content changes and implementing web application firewalls can provide additional layers of protection. The vulnerability highlights the importance of input validation in web applications and demonstrates how seemingly legitimate features can become attack vectors when proper security controls are not implemented. Organizations should also consider implementing principle of least privilege access controls to limit the potential impact of compromised accounts, ensuring that users have only the minimum permissions necessary to perform their duties.