CVE-2025-5842 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Modern Design Library plugin for WordPress, developed by butterflymedia. This vulnerability affects all versions up to and including 1.1.4. The root cause is insufficient input sanitization and output escaping of the 'class' parameter within the plugin's web page generation process. An attacker with authenticated Contributor-level access or higher can exploit this flaw by injecting arbitrary malicious scripts into pages. These scripts are then stored and executed in the context of any user who views the compromised page, enabling potential session hijacking, privilege escalation, or delivery of further malicious payloads. The vulnerability has a CVSS v3.1 base score of 6.4, indicating a medium severity level. The attack vector is network-based with low attack complexity, requiring privileges equivalent to a Contributor role, and no user interaction is needed for exploitation. The scope is changed, meaning the vulnerability affects resources beyond the initially compromised component, and it impacts confidentiality and integrity but not availability. No known exploits are currently reported in the wild, and no patches have been linked yet. This vulnerability falls under CWE-79, which is a common and critical web application security issue related to improper neutralization of input during web page generation.

For European organizations using WordPress websites with the Modern Design Library plugin, this vulnerability poses a significant risk to the confidentiality and integrity of their web applications and user data. Exploitation could lead to unauthorized script execution, enabling attackers to steal session cookies, deface websites, redirect users to malicious sites, or perform actions on behalf of legitimate users. This can damage brand reputation, lead to data breaches involving personal data protected under GDPR, and potentially result in financial losses or regulatory penalties. Since the vulnerability requires authenticated access at Contributor level or above, insider threats or compromised user accounts increase risk. The stored nature of the XSS means that once injected, the malicious script persists and affects all users accessing the infected pages, amplifying the impact. European organizations with public-facing WordPress sites, especially those in sectors like e-commerce, media, and government, are particularly vulnerable to reputational damage and compliance issues if exploited.

1. Immediate mitigation involves restricting Contributor-level permissions to trusted users only and auditing existing user roles to minimize risk exposure. 2. Monitor and review all content submitted by Contributors for suspicious or unexpected HTML or script content, especially in the 'class' attribute fields. 3. Implement Web Application Firewall (WAF) rules that detect and block common XSS payloads targeting the 'class' parameter in HTTP requests. 4. Employ Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of any injected scripts. 5. Regularly update the Modern Design Library plugin once the vendor releases a patch addressing this vulnerability. 6. Conduct security awareness training for content editors and contributors about the risks of XSS and safe content practices. 7. Use security plugins that provide real-time scanning and alerting for suspicious activities or injected scripts within WordPress environments. 8. Perform periodic security assessments and penetration tests focusing on input validation and output encoding in WordPress plugins.