CVE-2025-11770 is a stored Cross-Site Scripting (XSS) vulnerability identified in the BrightTALK WordPress Shortcode plugin developed by billybigpotatoes. The vulnerability exists in all versions up to and including 2.4.0 due to insufficient sanitization and escaping of the 'format' attribute within the brighttalk-time shortcode. This flaw allows authenticated users with contributor-level permissions or higher to inject arbitrary JavaScript code into WordPress pages. When other users access these pages, the injected scripts execute in their browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation) and has a CVSS v3.1 base score of 6.4, reflecting a medium severity level. The attack vector is network-based, requiring low attack complexity and privileges of at least contributor level, but no user interaction is needed for exploitation. The scope is changed as the vulnerability can affect other users viewing the injected content. No known exploits have been reported in the wild, and no official patches have been released as of the publication date. The vulnerability highlights the risks of insufficient input validation in WordPress plugins, especially those that allow user-generated content or shortcode attributes to be rendered directly in pages.

For European organizations, this vulnerability poses a moderate risk primarily to the confidentiality and integrity of user sessions and data on affected WordPress sites. Attackers with contributor access can embed malicious scripts that execute in the browsers of site visitors, potentially leading to credential theft, session hijacking, or unauthorized actions such as content manipulation or privilege escalation. While availability is not directly impacted, the reputational damage and potential data breaches could have significant consequences, especially for organizations subject to GDPR and other data protection regulations. The risk is heightened for organizations that allow external contributors or have less restrictive user role management. Since WordPress is widely used across Europe for corporate websites, blogs, and intranets, the vulnerability could affect a broad range of sectors including media, education, government, and e-commerce. The lack of a patch at disclosure means organizations must rely on interim mitigations to reduce exposure.

1. Immediately audit user roles and permissions to ensure that only trusted users have contributor-level or higher access. Restrict contributor permissions where possible. 2. Implement strict input validation and output escaping for all shortcode attributes, especially the 'format' attribute in brighttalk-time shortcodes, using WordPress security best practices. 3. Monitor WordPress pages and posts for suspicious or unexpected shortcode usage that could indicate exploitation attempts. 4. Employ Web Application Firewalls (WAFs) with custom rules to detect and block malicious script injections targeting the vulnerable shortcode. 5. Educate content contributors about the risks of injecting untrusted content and enforce content review workflows. 6. Stay updated with the plugin vendor’s announcements and apply official patches promptly once available. 7. Consider temporarily disabling or replacing the BrightTALK WordPress Shortcode plugin if immediate patching is not possible. 8. Use security plugins that scan for stored XSS and other common WordPress vulnerabilities to detect potential compromises early.