CVE-2025-4665: WordPress CFDB7 Plugin SQLi Vulnerability

CVE-2025-4665 Overview

WordPress plugin Contact Form CFDB7 versions up to and including 1.3.2 are affected by a pre-authentication SQL injection vulnerability that cascades into insecure deserialization (PHP Object Injection). The weakness arises due to insufficient validation of user input in plugin endpoints, allowing crafted input to influence backend queries in unexpected ways. Using specially crafted payloads, this can escalate into unsafe deserialization, enabling arbitrary object injection in PHP.

Critical Impact

This vulnerability allows unauthenticated attackers to perform SQL injection attacks that can escalate to PHP Object Injection, potentially leading to remote code execution, data exfiltration, or complete site compromise without requiring authentication.

Affected Products

• WordPress Contact Form CFDB7 plugin versions up to and including 1.3.2
• WordPress installations using vulnerable CFDB7 plugin versions
• Web servers hosting affected WordPress configurations

Discovery Timeline

• 2025-10-29 - CVE-2025-4665 published to NVD
• 2025-10-30 - Last updated in NVD database

Technical Details for CVE-2025-4665

Vulnerability Analysis

This vulnerability represents a chained attack scenario combining SQL Injection (CWE-89) with Insecure Deserialization vulnerabilities. The Contact Form CFDB7 plugin fails to properly sanitize user-supplied input before incorporating it into SQL queries executed against the WordPress database. This initial SQL injection weakness can be leveraged to manipulate serialized PHP data stored in the database, which when subsequently deserialized by the application, allows attackers to inject arbitrary PHP objects.

The attack chain is particularly dangerous because it does not require authentication - any visitor to a WordPress site running a vulnerable version of the plugin can potentially exploit this flaw. While exploitation does require a crafted interaction with the affected endpoint, the technical barrier to successful exploitation is relatively low for skilled attackers.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the CFDB7 plugin's endpoint handlers. User-supplied data is passed directly to database queries without proper sanitization or parameterized query usage. Additionally, the application's handling of serialized data lacks integrity verification, allowing manipulated serialized objects to be processed during deserialization operations.

Attack Vector

The attack is network-accessible and requires user interaction to trigger successfully. An attacker can craft malicious HTTP requests targeting the vulnerable plugin endpoints. The attack flow typically involves:

1. Initial SQL Injection: The attacker sends specially crafted input to the vulnerable endpoint that escapes the intended query context
2. Data Manipulation: Through SQL injection, the attacker can modify serialized data stored in the database or inject malicious serialized payloads
3. Object Injection: When the application deserializes the tampered data, arbitrary PHP objects are instantiated, potentially triggering dangerous magic methods that lead to code execution

The vulnerability is exploited through network-based requests that target specific plugin endpoints. Attackers craft payloads that bypass input validation, inject malicious SQL commands, and ultimately achieve PHP object injection through the deserialization chain. For detailed technical information, refer to the Mandiant Vulnerability Disclosure MNDT-2025-0006.

Detection Methods for CVE-2025-4665

Indicators of Compromise

• Unusual SQL error messages or database connection failures in WordPress error logs
• Unexpected serialized data patterns in database tables associated with CFDB7 plugin
• Anomalous HTTP requests to CFDB7 plugin endpoints containing SQL metacharacters or serialized PHP payloads
• Evidence of unauthorized data access or modification in contact form submission records

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block SQL injection patterns targeting WordPress plugins
• Monitor WordPress access logs for suspicious requests containing serialized PHP data or SQL injection signatures
• Deploy database activity monitoring to detect unusual query patterns or unauthorized data modifications
• Use file integrity monitoring to detect any unauthorized changes to WordPress core files or plugin directories

Monitoring Recommendations

• Enable detailed logging for the CFDB7 plugin and review logs regularly for anomalous activity
• Configure alerts for database queries containing union selects, time-based injection patterns, or serialized object signatures
• Monitor for new WordPress admin accounts or unexpected privilege changes that could indicate post-exploitation activity

How to Mitigate CVE-2025-4665

Immediate Actions Required

• Update the Contact Form CFDB7 plugin to a patched version as soon as one becomes available
• Temporarily disable or remove the CFDB7 plugin if no patch is available and the functionality is not critical
• Implement WAF rules to filter requests containing SQL injection or PHP serialization patterns
• Review database contents for signs of tampering or malicious serialized data

Patch Information

Organizations should monitor the WordPress Plugin Directory for Contact Form CFDB7 for security updates. Additionally, review the Mandiant Vulnerability Disclosure for detailed technical guidance and remediation recommendations.

Workarounds

• Deploy a Web Application Firewall with rules specifically designed to block SQL injection and PHP object injection attempts
• Restrict access to WordPress admin areas and plugin endpoints using IP whitelisting where feasible
• Consider using alternative contact form plugins until a patch is available for CFDB7
• Implement additional input validation at the web server level using ModSecurity or similar technologies

# Example WAF rule to block common SQL injection patterns (ModSecurity)
SecRule ARGS "@rx (?i)(union.*select|select.*from|insert.*into|update.*set|delete.*from)" \
    "id:1001,phase:2,deny,status:403,msg:'SQL Injection Attempt Blocked'"