CVE-2025-3515 is a high-severity vulnerability affecting the WordPress plugin 'Drag and Drop Multiple File Upload for Contact Form 7' developed by glenwpcoder. This vulnerability arises from insufficient validation of uploaded file types in all plugin versions up to and including 1.3.8.9. Specifically, the plugin fails to properly restrict dangerous file types, allowing unauthenticated attackers to bypass the blacklist and upload arbitrary files such as .phar archives. On servers configured to treat .phar files as executable PHP scripts—commonly default Apache servers using mod_php—this can lead to remote code execution (RCE). The attack vector requires no authentication or user interaction, and the exploit can be performed remotely over the network. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type), indicating a failure to enforce proper file type restrictions during upload. The CVSS 3.1 base score is 8.1 (high), reflecting the critical impact on confidentiality, integrity, and availability if exploited. Although no known exploits are currently reported in the wild, the ease of exploitation and potential for server compromise make this a significant threat to websites using this plugin. The lack of patch links suggests that a fix may not yet be publicly available, increasing the urgency for mitigation.

For European organizations, especially those relying on WordPress websites with the affected plugin, this vulnerability poses a substantial risk. Successful exploitation could lead to full server compromise, enabling attackers to execute arbitrary code, steal sensitive data, deface websites, or use compromised servers as a foothold for further attacks within corporate networks. This is particularly critical for organizations handling personal data under GDPR, as breaches could result in regulatory penalties and reputational damage. The vulnerability affects the availability and integrity of web services, potentially disrupting business operations. Since the plugin is popular among small to medium enterprises and agencies using Contact Form 7 for customer interactions, the attack surface is broad. Additionally, default Apache+mod_php configurations are common in many European hosting environments, increasing the likelihood of successful exploitation. The threat is amplified in sectors with high-value targets such as finance, healthcare, and government, where web presence is critical and data sensitivity is high.

1. Immediate mitigation involves disabling or removing the vulnerable plugin until a patch is released. 2. Implement strict web application firewall (WAF) rules to detect and block uploads of .phar and other potentially dangerous file types. 3. Harden server configurations by disabling execution of .phar files or any untrusted file extensions in web-accessible directories, for example by configuring Apache to deny execution of .phar files or by using PHP-FPM with strict file handling. 4. Employ file integrity monitoring to detect unauthorized file uploads or modifications. 5. Regularly audit and update all WordPress plugins and themes to their latest versions once patches are available. 6. Restrict file upload permissions and isolate upload directories with minimal privileges. 7. Monitor logs for suspicious upload activity and anomalous requests targeting the plugin's upload endpoints. 8. Educate site administrators on the risks of using outdated plugins and encourage proactive vulnerability management. These steps go beyond generic advice by focusing on server-level hardening and active monitoring tailored to this specific vulnerability.