CVE-2025-6740 in Contact Form 7 Database Addon Plugin
Summary
by MITRE • 07/04/2025
The Contact Form 7 Database Addon plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘tmpD’ parameter in all versions up to, and including, 1.3.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 07/04/2025
The Contact Form 7 Database Addon plugin represents a widely used extension for WordPress that enables administrators to store form submissions in the database. This particular vulnerability affects versions up to and including 1.3.1, creating a significant security risk for WordPress installations that rely on this plugin for form management and data collection. The flaw exists within the plugin's handling of the 'tmpD' parameter, which is processed through a vulnerable input validation mechanism that fails to properly sanitize user-supplied data before it is stored or rendered in web pages. This specific vulnerability classifies under CWE-79 which describes improper neutralization of input during web page generation, commonly known as cross-site scripting attacks.
The technical implementation of this vulnerability occurs when an attacker crafts malicious input containing script code within the 'tmpD' parameter and submits it through the plugin's form handling mechanism. Due to insufficient input sanitization, the malicious payload gets stored in the database without proper escaping or validation. When subsequent users access pages that display this stored data, the embedded scripts execute in their browsers within the context of the vulnerable website, potentially leading to session hijacking, defacement, or data theft. The vulnerability is particularly concerning because it operates without requiring authentication, allowing attackers to exploit it from any location on the internet, making it a prime target for automated exploitation.
The operational impact of this stored XSS vulnerability extends beyond simple script execution as it provides attackers with persistent access to user sessions and potentially sensitive data. Attackers can leverage this vulnerability to steal cookies, session tokens, and other authentication credentials from logged-in users who access affected pages. The attack surface is broad since any user who views pages containing the stored malicious data becomes a potential victim, including administrators who might access form submission records. This vulnerability also enables more sophisticated attacks such as credential phishing, where attackers can redirect victims to malicious sites or inject additional malicious scripts that harvest user information, making it a particularly dangerous threat to WordPress installations that rely on form data collection.
Mitigation strategies for this vulnerability should include immediate patching of the Contact Form 7 Database Addon plugin to version 1.3.2 or later, which contains the necessary input sanitization and output escaping fixes. Organizations should implement comprehensive input validation at multiple layers, ensuring that all user-supplied data is properly sanitized before database storage and appropriately escaped during output rendering. Network monitoring should be enhanced to detect suspicious parameter patterns and anomalous data submissions that might indicate exploitation attempts. Security configurations should include Content Security Policy headers to limit script execution capabilities, and regular security audits should be conducted to identify other potential XSS vulnerabilities in the WordPress ecosystem. Additionally, administrators should consider implementing web application firewalls and privileged access controls to minimize the impact of any successful exploitation attempts, aligning with ATT&CK technique T1566 for credential harvesting through malicious web content.