CVE-2025-11770 is a stored Cross-Site Scripting vulnerability identified in the BrightTALK WordPress Shortcode plugin, developed by billybigpotatoes. This vulnerability arises from improper neutralization of input during web page generation (CWE-79), specifically due to insufficient sanitization and escaping of the 'format' attribute within the brighttalk-time shortcode. All versions up to and including 2.4.0 are affected. An attacker with contributor-level or higher privileges can inject arbitrary JavaScript code into WordPress pages by manipulating the 'format' shortcode attribute. Because the injected script is stored, it executes every time a user accesses the infected page, potentially compromising user sessions, stealing cookies, or performing actions on behalf of users. The vulnerability requires authenticated access but no additional user interaction to trigger the payload. The CVSS v3.1 base score is 6.4, reflecting medium severity, with an attack vector of network, low attack complexity, privileges required at the contributor level, no user interaction, and a scope change. No patches or public exploits have been reported as of the publication date (November 21, 2025). The vulnerability is particularly concerning for sites that allow multiple contributors or editors, as it expands the attack surface to internal users. The lack of output escaping and input validation in the plugin's shortcode processing is the root cause, highlighting the importance of secure coding practices in WordPress plugin development.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of web applications running WordPress with the BrightTALK Shortcode plugin. Exploitation can lead to session hijacking, unauthorized actions performed on behalf of users, and potential data leakage. Since the vulnerability is stored XSS, it can affect any user visiting the compromised page, including administrators, increasing the risk of privilege escalation or site takeover. Organizations relying on WordPress for public-facing websites or internal portals with multiple contributors are particularly vulnerable. The medium CVSS score reflects that while the attack requires authenticated access, the low complexity and network vector make it feasible in environments with multiple content editors. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time. The impact on availability is minimal, but the integrity and confidentiality risks can lead to reputational damage, regulatory non-compliance (e.g., GDPR), and potential financial losses.

1. Immediately restrict contributor and higher-level privileges to trusted users only, minimizing the number of accounts that can exploit this vulnerability. 2. Implement a Web Application Firewall (WAF) with rules to detect and block malicious script injections targeting the 'format' attribute in the brighttalk-time shortcode. 3. Conduct a thorough audit of existing content for injected scripts or suspicious shortcode usage and remove any malicious payloads. 4. Monitor WordPress logs and user activities for unusual behavior indicative of exploitation attempts. 5. Encourage the vendor to release a patch and apply it promptly once available. 6. As a temporary measure, disable or remove the BrightTALK WordPress Shortcode plugin if feasible until a fix is released. 7. Educate content contributors about secure content practices and the risks of injecting untrusted code. 8. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected sites. 9. Regularly update WordPress core and plugins to reduce exposure to similar vulnerabilities. These steps go beyond generic advice by focusing on privilege management, active monitoring, and layered defenses tailored to the nature of this stored XSS vulnerability.