CVE-2025-6756 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the Ultra Addons for Contact Form 7 WordPress plugin developed by themefic. This vulnerability exists in all versions up to and including 3.5.21. The root cause is improper neutralization of input during web page generation, specifically insufficient sanitization and escaping of user-supplied attributes in the UACF7_CUSTOM_FIELDS shortcode. Authenticated attackers with contributor-level privileges or higher can exploit this flaw by injecting arbitrary malicious scripts into pages. These scripts execute whenever any user accesses the compromised page, potentially leading to session hijacking, defacement, or redirection to malicious sites. The vulnerability has a CVSS 3.1 base score of 6.4 (medium severity), with an attack vector of network, low attack complexity, requiring privileges (PR:L), no user interaction, and a scope change. The impact affects confidentiality and integrity but not availability. No known exploits are reported in the wild yet, and no official patches have been linked at the time of publication. This vulnerability is significant because Contact Form 7 is a widely used WordPress plugin, and Ultra Addons extends its functionality, making it a common target in WordPress environments. The ability for relatively low-privileged authenticated users to inject persistent scripts increases the threat surface, especially in multi-user WordPress sites such as corporate blogs, e-commerce, and community portals.

For European organizations, this vulnerability poses a moderate risk primarily to websites running WordPress with the Ultra Addons for Contact Form 7 plugin installed. Exploitation could lead to unauthorized disclosure of sensitive information (e.g., session tokens, personal data), defacement of public-facing websites, or distribution of malware to visitors, damaging organizational reputation and trust. Since the attack requires contributor-level access, insider threats or compromised user accounts are the main vectors. Organizations with multi-user WordPress environments, such as media companies, educational institutions, and SMEs, are particularly vulnerable. GDPR implications arise if personal data is exposed or manipulated, potentially leading to regulatory penalties. The vulnerability does not directly affect availability, so denial of service is unlikely. However, the integrity and confidentiality risks can facilitate further attacks or data breaches. The lack of a patch at publication means organizations must act promptly to mitigate risk. Given WordPress's popularity in Europe, the threat could impact a broad range of sectors relying on WordPress for their web presence.

1. Immediate mitigation involves restricting contributor-level access to trusted users only and auditing existing user privileges to minimize the risk of exploitation. 2. Disable or remove the Ultra Addons for Contact Form 7 plugin if it is not essential to reduce the attack surface. 3. Implement Web Application Firewall (WAF) rules that detect and block suspicious payloads targeting the UACF7_CUSTOM_FIELDS shortcode parameters. 4. Monitor website logs for unusual script injection attempts or unexpected changes in page content. 5. Apply strict Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected pages. 6. Regularly update WordPress core and plugins; once a patch is released for this vulnerability, prioritize its deployment. 7. Educate site administrators and contributors about the risks of XSS and safe content management practices. 8. Conduct security reviews and penetration testing focused on plugin vulnerabilities and user privilege abuse. These steps go beyond generic advice by focusing on access control, monitoring, and compensating controls until an official patch is available.