CVE-2025-30973: CoSchool LMS Deserialization Vulnerability

CVE-2025-30973 Overview

CVE-2025-30973 is a critical Insecure Deserialization vulnerability affecting the CoSchool LMS WordPress plugin developed by Codexpert, Inc. The vulnerability allows attackers to perform PHP Object Injection attacks by exploiting improper handling of serialized data. This flaw enables unauthenticated remote attackers to inject arbitrary PHP objects, potentially leading to complete site compromise.

Critical Impact

Unauthenticated attackers can exploit this PHP Object Injection vulnerability to achieve remote code execution, data theft, or complete WordPress site takeover without any user interaction required.

Affected Products

• CoSchool LMS versions from n/a through 1.4.3
• WordPress installations running vulnerable CoSchool LMS plugin
• All web servers hosting affected CoSchool LMS configurations

Discovery Timeline

• 2025-07-16 - CVE-2025-30973 published to NVD
• 2025-07-16 - Last updated in NVD database

Technical Details for CVE-2025-30973

Vulnerability Analysis

This vulnerability stems from unsafe deserialization of user-controlled input within the CoSchool LMS WordPress plugin. PHP Object Injection (CWE-502) occurs when an application deserializes untrusted data using functions like unserialize() without proper validation. In the context of WordPress plugins, this type of vulnerability is particularly dangerous because attackers can leverage existing "magic methods" (such as __wakeup(), __destruct(), or __toString()) present in the WordPress core or other installed plugins to construct a Property Oriented Programming (POP) chain.

The network-accessible nature of this vulnerability means attackers can exploit it remotely without authentication. When combined with the right POP chain gadgets, successful exploitation can result in arbitrary file operations, SQL injection, or remote code execution on the underlying web server.

Root Cause

The root cause of CVE-2025-30973 is the use of PHP's unserialize() function on user-supplied input without adequate sanitization or type restrictions. The CoSchool LMS plugin fails to validate the integrity and source of serialized data before processing it, allowing malicious serialized objects to be reconstructed by the application. This violates the security principle of never trusting user input, especially when that input is used in operations that can instantiate arbitrary objects.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can craft a malicious HTTP request containing a specially constructed serialized PHP object. When the vulnerable CoSchool LMS endpoint processes this request and deserializes the payload, the injected object is instantiated. If suitable gadget classes exist in the application's codebase (including WordPress core, themes, or other plugins), the attacker can chain method calls to achieve various malicious outcomes.

The exploitation flow typically involves:

1. Identifying the vulnerable deserialization endpoint in CoSchool LMS
2. Analyzing available classes for exploitable magic methods (POP chain construction)
3. Crafting a serialized payload that chains object instantiation to achieve code execution
4. Sending the payload via an unauthenticated HTTP request to the vulnerable endpoint

Due to the absence of verified code examples, readers should consult the Patchstack security advisory for detailed technical analysis of the exploitation mechanism.

Detection Methods for CVE-2025-30973

Indicators of Compromise

• Unusual POST requests to CoSchool LMS endpoints containing serialized PHP data (look for O: prefixed strings in request bodies)
• Unexpected file creations or modifications in the WordPress installation directory
• Web server logs showing requests with base64-encoded or URL-encoded serialized object payloads
• Anomalous PHP process execution or outbound connections from the web server

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in HTTP requests
• Monitor WordPress plugin directories for unauthorized file changes or new PHP files
• Implement file integrity monitoring on the CoSchool LMS plugin directory
• Review web server access logs for suspicious POST requests targeting CoSchool LMS endpoints

Monitoring Recommendations

• Enable verbose logging for WordPress and the web server to capture detailed request information
• Set up real-time alerts for detection of serialized object patterns (O:[0-9]+:) in incoming requests
• Monitor for privilege escalation attempts or unauthorized administrative actions in WordPress
• Track outbound network connections from the web server process for potential reverse shell indicators

How to Mitigate CVE-2025-30973

Immediate Actions Required

• Update CoSchool LMS plugin immediately to a patched version beyond 1.4.3 when available
• Temporarily deactivate the CoSchool LMS plugin if a patch is not yet available and the functionality is not critical
• Implement WAF rules to block requests containing serialized PHP object signatures
• Review WordPress user accounts and audit for any unauthorized administrative users

Patch Information

Organizations should monitor the WordPress plugin repository and the Patchstack security database for official patch releases from Codexpert, Inc. Until a patch is available, defensive measures should be implemented at the WAF and server configuration level.

Workarounds

• Disable the CoSchool LMS plugin entirely until a patched version is released
• Restrict network access to WordPress admin interfaces using IP allowlisting
• Implement a WAF rule to block requests containing PHP serialization patterns
• Consider using WordPress security plugins that provide virtual patching capabilities

# Configuration example - Apache mod_security rule to block PHP serialization attacks
# Add to .htaccess or Apache configuration
SecRule REQUEST_BODY "@rx O:[0-9]+:\"[a-zA-Z_]+\"" \
    "id:1001,phase:2,deny,status:403,msg:'Blocked PHP Object Injection attempt'"