CVE-2025-5950 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the IndieBlocks plugin for WordPress, developed by janboddez. This vulnerability exists in all versions up to and including 0.13.2. The root cause is improper neutralization of input during web page generation, specifically insufficient sanitization and escaping of the 'kind' parameter. An authenticated attacker with Contributor-level privileges or higher can exploit this flaw by injecting arbitrary malicious scripts into pages generated by the plugin. These scripts are then stored persistently and executed in the browsers of any users who visit the compromised pages. The vulnerability has a CVSS v3.1 base score of 6.4, indicating a medium severity level. The attack vector is network-based (remote), with low attack complexity and requiring privileges (Contributor or above). No user interaction is needed for the malicious script to execute once the page is accessed, and the scope is changed, meaning the vulnerability affects components beyond the vulnerable plugin itself. The impact includes limited confidentiality and integrity loss, as the attacker can execute scripts in the context of the affected site, potentially stealing session cookies, performing actions on behalf of users, or defacing content. Availability is not impacted. No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability is classified under CWE-79, which covers improper neutralization of input leading to XSS attacks.

For European organizations using WordPress sites with the IndieBlocks plugin, this vulnerability poses a significant risk to web application security and user trust. Attackers with Contributor-level access can inject persistent malicious scripts that execute in the browsers of site visitors, potentially leading to session hijacking, unauthorized actions, or distribution of malware. This can result in data breaches involving user credentials or personal data, violating GDPR requirements and leading to regulatory penalties. The integrity of website content can be compromised, damaging brand reputation and user confidence. Although availability is not directly affected, the indirect consequences of exploitation—such as blacklisting by search engines or browsers—can disrupt normal business operations. Organizations in sectors with high reliance on web presence, such as e-commerce, media, and public services, are particularly vulnerable. The medium CVSS score reflects that while exploitation requires authenticated access, the low complexity and lack of user interaction make it a realistic threat, especially in environments with multiple contributors or weak access controls.

1. Immediate mitigation should include restricting Contributor-level access to trusted users only and reviewing existing user roles to minimize unnecessary privileges. 2. Implement strict input validation and output encoding on the 'kind' parameter within the IndieBlocks plugin code, ensuring all user-supplied data is properly sanitized before rendering. 3. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the 'kind' parameter. 4. Monitor logs for unusual activity from Contributor accounts, including unexpected content changes or script injections. 5. Educate content contributors about secure content practices and the risks of injecting untrusted code. 6. Since no official patch is available yet, consider temporarily disabling the IndieBlocks plugin or isolating it in a staging environment until a secure version is released. 7. Regularly update WordPress core and all plugins to the latest versions to reduce exposure to known vulnerabilities. 8. Conduct periodic security audits and penetration tests focusing on user input handling and privilege management. 9. Implement Content Security Policy (CSP) headers to limit the impact of any injected scripts by restricting allowed script sources.