CVE-2025-13159 is a stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, found in the Flo Forms – Easy Drag & Drop Form Builder plugin for WordPress. The vulnerability exists because the plugin permits unauthenticated users to upload SVG files through an AJAX endpoint named `flo_form_submit` without performing adequate file content validation. SVG files can contain embedded JavaScript, which, when uploaded maliciously, can execute in the context of the WordPress admin interface. This execution occurs when an administrator views the uploaded SVG file, enabling attackers to run arbitrary scripts. Such scripts can lead to session hijacking, privilege escalation, or full site compromise, including defacement, data theft, or installation of backdoors. The vulnerability affects all plugin versions up to and including 1.0.43. The CVSS 3.1 base score is 7.1, indicating a high severity due to network attack vector, no privileges required, low attack complexity, requirement for user interaction (admin viewing the file), and a scope change impacting confidentiality, integrity, and availability. No known exploits have been reported in the wild yet, but the ease of exploitation and potential impact make it a significant threat. The lack of patch links suggests a patch may not yet be available, increasing urgency for mitigation.

For European organizations, this vulnerability poses a significant risk to websites running WordPress with the vulnerable Flo Forms plugin installed. Exploitation can lead to full site compromise, which may result in data breaches, defacement, loss of customer trust, and disruption of business operations. Given the widespread use of WordPress across Europe, especially among small and medium enterprises and public sector websites, the attack surface is considerable. Compromised sites could be used to distribute malware, conduct phishing campaigns, or serve as pivot points for further network intrusions. The impact on confidentiality, integrity, and availability is high, potentially affecting sensitive customer data and critical business functions. Additionally, regulatory implications under GDPR may arise if personal data is exposed or mishandled due to exploitation.

1. Immediately disable SVG file uploads in the Flo Forms plugin or globally in WordPress until a secure patch is released. 2. Restrict access to the `flo_form_submit` AJAX endpoint by implementing authentication and authorization checks to prevent unauthenticated uploads. 3. Implement server-side validation to strictly verify uploaded file types and sanitize SVG content to remove any embedded scripts. 4. Monitor WordPress admin activity logs for unusual SVG uploads or admin interactions with uploaded files. 5. Educate administrators to avoid opening or previewing untrusted SVG files in the admin interface. 6. Apply security plugins that can detect and block malicious file uploads and XSS payloads. 7. Once available, promptly apply official patches from the vendor. 8. Conduct regular security audits and vulnerability scans focusing on WordPress plugins. 9. Consider employing Content Security Policy (CSP) headers to limit script execution in the admin interface. 10. Backup WordPress sites regularly to enable quick recovery in case of compromise.