CVE-2026-25358: Meloo Object Injection Vulnerability

CVE-2026-25358 Overview

A Deserialization of Untrusted Data vulnerability has been identified in the Meloo WordPress theme developed by rascals. This vulnerability allows attackers to perform PHP Object Injection attacks, potentially leading to remote code execution, data manipulation, or complete site compromise.

Critical Impact

Authenticated attackers can exploit insecure deserialization to inject malicious PHP objects, potentially achieving remote code execution or full WordPress site takeover.

Affected Products

• Meloo WordPress Theme versions prior to 2.8.2
• WordPress installations using vulnerable Meloo theme versions

Discovery Timeline

• 2026-03-25 - CVE CVE-2026-25358 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-25358

Vulnerability Analysis

This vulnerability is classified under CWE-502 (Deserialization of Untrusted Data). The Meloo WordPress theme fails to properly validate and sanitize serialized data before deserializing it, creating an attack vector for PHP Object Injection. When untrusted data is passed to PHP's unserialize() function without adequate validation, an attacker can craft malicious serialized objects that execute arbitrary code or manipulate application logic upon deserialization.

The attack requires low-privilege authentication (such as a subscriber or contributor role on the WordPress site) but does not require user interaction, making it exploitable in automated attack scenarios. The vulnerability can result in complete compromise of confidentiality, integrity, and availability of the affected WordPress installation.

Root Cause

The root cause is the insecure use of PHP deserialization functions on user-controllable input. The Meloo theme processes serialized data from user input without implementing proper safeguards such as:

• Signature verification of serialized data
• Allowlisting of permitted classes for deserialization
• Input validation prior to deserialization
• Using safer alternatives like JSON encoding

Attack Vector

The vulnerability is exploitable over the network by authenticated users with low privileges. An attacker crafts a malicious serialized PHP object containing payload properties designed to execute arbitrary code through "magic methods" like __wakeup(), __destruct(), or __toString(). When the vulnerable theme deserializes this crafted input, the malicious object is instantiated and the payload executes with the privileges of the web server process.

The attack chain typically involves:

1. Identifying gadget chains within WordPress core, plugins, or the theme itself
2. Crafting a serialized object that leverages these gadgets
3. Submitting the payload through the vulnerable input vector
4. Triggering deserialization to execute the malicious code

For detailed technical information about this vulnerability, see the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-25358

Indicators of Compromise

• Unusual PHP serialized data in request parameters or POST bodies containing unexpected class names
• Web server logs showing requests with base64-encoded or URL-encoded serialized PHP objects
• Unexpected file creations or modifications in the WordPress directory structure
• New or modified user accounts with elevated privileges
• Suspicious outbound network connections from the web server

Detection Strategies

• Monitor web application firewall logs for patterns matching PHP serialized object syntax (e.g., O: followed by class definitions)
• Implement file integrity monitoring on WordPress core files, theme files, and plugin directories
• Review authentication logs for privilege escalation attempts or unusual user activity
• Deploy runtime application self-protection (RASP) solutions to detect deserialization attacks
• Analyze PHP error logs for object instantiation errors that may indicate exploitation attempts

Monitoring Recommendations

• Enable verbose logging for the Meloo theme and related WordPress components
• Configure alerts for file system changes within the wp-content/themes/meloo/ directory
• Monitor for new scheduled tasks (wp-cron) or unexpected admin users
• Implement network-level monitoring for command-and-control traffic patterns

How to Mitigate CVE-2026-25358

Immediate Actions Required

• Update the Meloo WordPress theme to version 2.8.2 or later immediately
• Audit existing user accounts for unauthorized privilege escalation
• Review recent file changes for signs of compromise
• Consider temporarily disabling the theme if immediate patching is not possible
• Implement web application firewall rules to block serialized PHP object payloads

Patch Information

The vendor has addressed this vulnerability in Meloo theme version 2.8.2. Administrators should update through the WordPress admin dashboard or by downloading the patched version directly from the theme vendor. After updating, verify the theme version is 2.8.2 or higher by navigating to Appearance > Themes in the WordPress admin panel.

For additional details, consult the Patchstack Vulnerability Report.

Workarounds

• Restrict access to authenticated WordPress functionality to trusted users only
• Implement strict user role management, limiting low-privilege accounts
• Deploy a web application firewall with rules targeting PHP object injection patterns
• Consider using security plugins that provide runtime protection against deserialization attacks
• Disable the Meloo theme temporarily and switch to a default WordPress theme until patching is complete

# WordPress CLI command to check current theme version
wp theme list --status=active --fields=name,version

# Update Meloo theme via WP-CLI
wp theme update meloo

# Verify the update was successful
wp theme get meloo --field=version