CVE-2025-4055 is a medium-severity Stored Cross-Site Scripting (XSS) vulnerability affecting the Multiple Post Type Order WordPress plugin developed by josj404. This vulnerability exists in all versions up to and including 1.10.0. The root cause is improper neutralization of user-supplied input in the plugin's 'mpto' shortcode, where insufficient input sanitization and output escaping allow authenticated users with contributor-level privileges or higher to inject arbitrary JavaScript code. When a page containing the malicious shortcode is accessed by any user, the injected script executes in their browser context. The vulnerability leverages CWE-79, which pertains to improper neutralization of input during web page generation. The CVSS v3.1 base score is 6.4, reflecting a medium severity level, with an attack vector of network (remote), low attack complexity, requiring privileges (contributor or above), no user interaction, and a scope change. The impact includes limited confidentiality and integrity loss, but no availability impact. No known exploits in the wild have been reported as of the publication date (May 7, 2025). The vulnerability is particularly dangerous because it allows privilege escalation from contributor-level users to execute scripts that can affect other users, potentially leading to session hijacking, defacement, or further exploitation within the WordPress environment. Since the vulnerability affects a WordPress plugin, it is relevant to any organization using this plugin on their WordPress sites. The absence of an official patch link suggests that mitigation may currently rely on manual workarounds or plugin updates pending release.

For European organizations, the impact of CVE-2025-4055 can be significant, especially for those relying on WordPress for their public-facing websites, intranets, or content management systems where the Multiple Post Type Order plugin is installed. The vulnerability allows authenticated contributors or higher to inject persistent malicious scripts, which can compromise the confidentiality of user data through session hijacking or credential theft, and integrity by altering displayed content or injecting misleading information. This can damage organizational reputation, lead to data breaches, and potentially facilitate further attacks such as phishing or malware distribution. Given the widespread use of WordPress across Europe, including in government, education, and private sectors, exploitation could disrupt trust in digital services. The scope change in the CVSS vector indicates that the vulnerability can affect components beyond the initially compromised plugin, potentially impacting other parts of the WordPress site or integrated systems. However, the requirement for contributor-level access limits exploitation to insiders or compromised accounts, somewhat reducing the risk from external anonymous attackers but increasing the threat from insider misuse or compromised credentials.

1. Immediate mitigation should include restricting contributor-level access to trusted users only and auditing existing contributor accounts for suspicious activity. 2. Disable or remove the Multiple Post Type Order plugin if it is not essential to reduce the attack surface. 3. Monitor WordPress sites for unusual shortcode usage or injected scripts, employing web application firewalls (WAFs) with rules targeting XSS payloads in shortcode attributes. 4. Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on affected sites. 5. Regularly update the plugin to the latest version once a patch is released by the vendor. 6. Educate content contributors about the risks of injecting untrusted content and enforce strict content validation policies. 7. Conduct periodic security assessments and penetration testing focusing on WordPress plugins and user privilege management. 8. Use security plugins that can detect and block XSS attempts and monitor for changes in shortcode content.