CVE-2025-48289: Kids Planet Object Injection Vulnerability

CVE-2025-48289 Overview

CVE-2025-48289 is a critical Insecure Deserialization vulnerability affecting the Kids Planet WordPress theme by AncoraThemes. The vulnerability allows unauthenticated attackers to exploit PHP Object Injection through deserialization of untrusted data, potentially leading to remote code execution, unauthorized data access, or complete site compromise.

Critical Impact

Unauthenticated attackers can exploit this PHP Object Injection vulnerability to potentially execute arbitrary code, manipulate database contents, or gain full administrative control over affected WordPress installations.

Affected Products

• AncoraThemes Kids Planet WordPress theme versions through 2.2.14

Discovery Timeline

• 2025-05-23 - CVE-2025-48289 published to NVD
• 2025-05-23 - Last updated in NVD database

Technical Details for CVE-2025-48289

Vulnerability Analysis

This vulnerability stems from improper handling of serialized data within the Kids Planet WordPress theme. When the application deserializes user-controlled input without adequate validation, attackers can inject malicious PHP objects that get instantiated during the deserialization process.

PHP Object Injection vulnerabilities are particularly dangerous in WordPress environments because themes and plugins often include classes with magic methods (__destruct(), __wakeup(), __toString()) that can be leveraged as "gadget chains" to achieve arbitrary code execution or other malicious outcomes.

The attack can be executed remotely over the network without requiring any authentication or user interaction, making it highly exploitable in real-world scenarios.

Root Cause

The root cause is the use of PHP's unserialize() function on untrusted user input without proper sanitization or type validation (CWE-502: Deserialization of Untrusted Data). The theme fails to implement allowlist-based filtering or alternative safe serialization methods such as json_encode()/json_decode().

Attack Vector

The vulnerability is exploitable over the network by unauthenticated attackers. An attacker crafts a malicious serialized PHP object payload containing references to existing classes within the WordPress installation that have exploitable magic methods. When this payload is processed by the vulnerable deserialization function, the injected object is instantiated and its magic methods are triggered, executing attacker-controlled code.

The exploitation process typically involves:

1. Identifying gadget chains within WordPress core, plugins, or other themes
2. Crafting a serialized payload that chains these gadgets to achieve code execution
3. Submitting the payload to the vulnerable endpoint
4. The server deserializes the payload, triggering the gadget chain and executing malicious code

For detailed technical information about this vulnerability, refer to the Patchstack security advisory.

Detection Methods for CVE-2025-48289

Indicators of Compromise

• Unexpected serialized data patterns in HTTP request parameters, particularly containing O: object notation
• Anomalous POST requests to theme-specific endpoints with base64-encoded or URL-encoded serialized payloads
• Creation of unauthorized administrator accounts or modification of existing user privileges
• Unexpected file modifications in WordPress directories, especially PHP files in theme or plugin folders
• Suspicious PHP error logs referencing unserialize() or class instantiation errors

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in incoming requests
• Monitor web server access logs for suspicious POST requests containing serialized data signatures (a:, O:, s:)
• Implement file integrity monitoring on WordPress core files, themes, and plugins directories
• Configure intrusion detection systems to alert on patterns associated with PHP object injection attempts

Monitoring Recommendations

• Enable detailed WordPress debug logging and review for deserialization-related errors
• Set up real-time alerting for unauthorized administrative actions or user privilege changes
• Monitor outbound network connections from the web server for potential reverse shell activity
• Regularly audit installed themes and plugins for known vulnerabilities using security scanning tools

How to Mitigate CVE-2025-48289

Immediate Actions Required

• Update the Kids Planet theme to a patched version immediately if one is available from AncoraThemes
• If no patch is available, consider temporarily disabling or replacing the Kids Planet theme with a secure alternative
• Implement WAF rules to block serialized PHP object payloads at the network perimeter
• Review WordPress user accounts for any unauthorized administrator accounts that may indicate prior exploitation
• Conduct a full site backup before making any changes to ensure recovery options

Patch Information

Check with AncoraThemes for an updated version of the Kids Planet theme that addresses this vulnerability. Monitor the Patchstack advisory for patch availability and update instructions.

Workarounds

• Deploy ModSecurity or similar WAF with rules targeting PHP serialization patterns in request data
• Implement a virtual patch at the application firewall level to filter malicious payloads
• Restrict access to the WordPress admin area by IP allowlisting where feasible
• Consider using a security plugin that provides runtime application self-protection (RASP) capabilities

# ModSecurity rule example to block PHP serialized object injection
SecRule REQUEST_BODY "@rx O:\d+:\"[a-zA-Z_]" \
    "id:1001,phase:2,deny,status:403,msg:'Potential PHP Object Injection Blocked'"