CVE-2025-68526: Modal Popup Box Object Injection Flaw

CVE-2025-68526 Overview

CVE-2025-68526 is an insecure deserialization vulnerability affecting the Modal Popup Box WordPress plugin developed by A WP Life. The vulnerability allows authenticated attackers to inject malicious PHP objects through untrusted data deserialization, potentially leading to complete site compromise. This PHP Object Injection flaw enables attackers with low-level privileges to achieve significant impact on confidentiality, integrity, and availability of affected WordPress installations.

Critical Impact

Authenticated attackers can exploit this PHP Object Injection vulnerability to execute arbitrary code, manipulate data, or cause denial of service on vulnerable WordPress sites running Modal Popup Box version 1.6.1 or earlier.

Affected Products

• Modal Popup Box WordPress Plugin versions up to and including 1.6.1
• WordPress installations using the vulnerable modal-popup-box plugin
• Websites with authenticated users (Subscriber level or higher) accessing the affected functionality

Discovery Timeline

• 2026-02-20 - CVE-2025-68526 published to NVD
• 2026-02-24 - Last updated in NVD database

Technical Details for CVE-2025-68526

Vulnerability Analysis

This vulnerability is classified under CWE-502 (Deserialization of Untrusted Data), a critical weakness that occurs when an application deserializes data from an untrusted source without proper validation. In the context of PHP applications like this WordPress plugin, object injection vulnerabilities arise when user-controlled input is passed to PHP's unserialize() function.

The attack can be performed over the network and requires only low-level authentication (such as a WordPress Subscriber account). No user interaction is required to exploit this vulnerability, making it particularly dangerous in multi-user WordPress environments.

Root Cause

The root cause of CVE-2025-68526 lies in improper handling of serialized PHP data within the Modal Popup Box plugin. When the plugin processes certain input parameters, it deserializes data without adequately verifying its integrity or origin. This allows an attacker to craft malicious serialized PHP objects that, when deserialized, can trigger dangerous "magic methods" (such as __wakeup(), __destruct(), or __toString()) present in the application or its dependencies.

Attack Vector

The attack vector for this vulnerability is network-based, requiring authenticated access to the WordPress installation. An attacker with minimal privileges can submit specially crafted serialized PHP payloads through plugin functionality. When the vulnerable code deserializes this malicious input, it can instantiate arbitrary PHP objects and potentially chain them together using Property-Oriented Programming (POP chains) techniques.

The exploitation typically involves:

1. Identifying a gadget chain within WordPress core, the vulnerable plugin, or other installed plugins/themes
2. Constructing a serialized payload that leverages these gadgets
3. Submitting the payload through the vulnerable input vector
4. Achieving code execution, file manipulation, or other malicious outcomes when deserialization occurs

For detailed technical analysis of this vulnerability, refer to the Patchstack Vulnerability Report.

Detection Methods for CVE-2025-68526

Indicators of Compromise

• Unusual PHP object strings appearing in request parameters or database entries containing serialized data with unexpected class names
• Web application firewall logs showing requests with O: prefixed strings (PHP serialized object notation) targeting the Modal Popup Box plugin endpoints
• Unexpected file modifications or new files created in WordPress directories following authenticated user activity
• Anomalous database changes or new administrator accounts created without legitimate authorization

Detection Strategies

• Monitor web server access logs for POST requests to Modal Popup Box plugin endpoints containing serialized PHP object patterns (O:[0-9]+:")
• Implement Web Application Firewall (WAF) rules to detect and block PHP serialized object injection attempts
• Review WordPress audit logs for suspicious activity from low-privileged user accounts interacting with popup functionality
• Deploy file integrity monitoring to detect unauthorized changes to WordPress core, plugin, and theme files

Monitoring Recommendations

• Enable comprehensive logging for all WordPress plugin API calls and administrative actions
• Configure security plugins to alert on serialized data patterns in HTTP request parameters
• Monitor for unusual outbound network connections from the web server that may indicate successful exploitation
• Implement real-time alerting for any new user account creation or privilege escalation events

How to Mitigate CVE-2025-68526

Immediate Actions Required

• Update the Modal Popup Box plugin to a patched version when available from the vendor
• Temporarily deactivate the Modal Popup Box plugin if a patch is not yet available and popup functionality is not critical
• Review and audit all user accounts, removing any unnecessary accounts with authenticated access
• Implement Web Application Firewall rules to block requests containing PHP serialized object patterns

Patch Information

Check the Patchstack Vulnerability Report for the latest patch information and updated plugin versions. WordPress administrators should monitor the official plugin repository for security updates to Modal Popup Box versions above 1.6.1.

Workarounds

• Restrict user registration and minimize the number of authenticated users on the WordPress installation
• Implement additional authentication controls such as two-factor authentication for all user accounts
• Use a security plugin with virtual patching capabilities to filter malicious serialized payloads
• Consider placing the site behind a WAF with PHP object injection detection rules enabled

# Disable the vulnerable plugin via WP-CLI until patched
wp plugin deactivate modal-popup-box

# List all users to audit for unnecessary accounts
wp user list --fields=ID,user_login,user_email,roles

# Check plugin version to confirm vulnerability status
wp plugin get modal-popup-box --fields=name,version,status