CVE-2026-25029: KIDZ Object Injection Vulnerability

CVE-2026-25029 Overview

CVE-2026-25029 is a critical Insecure Deserialization vulnerability affecting the KIDZ WordPress theme developed by park_of_ideas. This vulnerability allows unauthenticated attackers to exploit PHP Object Injection by sending maliciously crafted serialized data to the vulnerable application. When the application deserializes untrusted user input without proper validation, attackers can instantiate arbitrary PHP objects, potentially leading to remote code execution, data manipulation, or complete system compromise.

Critical Impact

This PHP Object Injection vulnerability in the KIDZ WordPress theme allows unauthenticated remote attackers to inject malicious objects, potentially achieving remote code execution or complete site takeover through deserialization of untrusted data.

Affected Products

• KIDZ WordPress Theme versions up to and including 5.24
• WordPress installations running the vulnerable KIDZ theme
• Websites utilizing park_of_ideas KIDZ theme without security patches

Discovery Timeline

• 2026-03-25 - CVE-2026-25029 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-25029

Vulnerability Analysis

This vulnerability stems from CWE-502 (Deserialization of Untrusted Data), a well-known weakness class that occurs when applications deserialize data from untrusted sources without adequate validation. In the context of the KIDZ WordPress theme, the application processes serialized PHP data that can be manipulated by an attacker to inject arbitrary objects into the application's execution flow.

PHP Object Injection vulnerabilities are particularly dangerous in WordPress environments because themes and plugins often include classes with "magic methods" such as __wakeup(), __destruct(), or __toString(). When a malicious serialized object is passed to unserialize(), these magic methods execute automatically, allowing attackers to chain together existing class methods (known as "POP chains" or Property Oriented Programming) to achieve code execution.

The attack requires no authentication and can be executed over the network, making it trivially exploitable for attackers with basic knowledge of PHP serialization mechanisms.

Root Cause

The root cause of CVE-2026-25029 is the improper handling of user-controlled serialized data within the KIDZ theme. The application likely uses PHP's native unserialize() function on input that can be influenced by external users without implementing proper input validation, type checking, or allowlist-based deserialization controls.

WordPress themes should never deserialize user-supplied data directly. Instead, they should use safer alternatives such as JSON encoding/decoding, or implement strict validation of serialized data before processing.

Attack Vector

The attack vector is network-based and requires no user interaction or privileges. An attacker can craft a malicious HTTP request containing a specially formatted serialized PHP object. When the KIDZ theme processes this request and deserializes the payload, the injected objects are instantiated with attacker-controlled properties.

The exploitation flow typically involves:

1. Identifying an entry point where serialized data is accepted (form fields, cookies, GET/POST parameters)
2. Discovering available PHP classes with exploitable magic methods
3. Constructing a POP chain that achieves the desired malicious outcome
4. Encoding the payload as a serialized PHP string
5. Submitting the payload to trigger deserialization and code execution

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

Detection Methods for CVE-2026-25029

Indicators of Compromise

• Unusual HTTP requests containing PHP serialized object patterns (strings starting with O:, a:, or s: followed by numeric values)
• Web server logs showing suspicious POST data with serialized PHP payloads
• Unexpected file creations or modifications in WordPress theme directories
• New administrator accounts or modified user privileges without authorization
• Anomalous outbound network connections from the web server

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block PHP serialized object patterns in user input
• Monitor access logs for requests containing serialization indicators targeting theme endpoints
• Deploy file integrity monitoring on WordPress installations to detect unauthorized changes
• Utilize endpoint detection solutions to identify post-exploitation behavior such as webshell deployment

Monitoring Recommendations

• Enable verbose logging for all HTTP requests to WordPress theme endpoints
• Configure SIEM alerts for patterns matching PHP object injection attempts
• Implement real-time monitoring for new file creation in WordPress directories
• Review WordPress user account creation and privilege modification events regularly

How to Mitigate CVE-2026-25029

Immediate Actions Required

• Update the KIDZ WordPress theme to a patched version immediately if available from park_of_ideas
• If no patch is available, consider temporarily disabling or replacing the KIDZ theme
• Implement WAF rules to block requests containing PHP serialized data to theme endpoints
• Audit WordPress installations for signs of compromise before and after remediation
• Review and remove any suspicious files, user accounts, or configuration changes

Patch Information

Security patches for this vulnerability should be obtained from the theme developer park_of_ideas or through the WordPress theme repository. Site administrators should verify the authenticity of any updates before installation. For the latest patch status and remediation guidance, consult the Patchstack Vulnerability Report.

SentinelOne Singularity provides comprehensive protection against exploitation attempts targeting this vulnerability through behavioral AI detection and real-time threat prevention capabilities.

Workarounds

• Implement input validation at the web server or WAF level to reject serialized PHP data patterns
• Consider using a security plugin that provides virtual patching for known WordPress vulnerabilities
• Restrict access to WordPress admin and theme functionality to trusted IP addresses where feasible
• Enable WordPress audit logging to detect and respond to suspicious activity promptly

# WAF rule example to block PHP serialized objects (ModSecurity format)
SecRule REQUEST_BODY "@rx O:\d+:\"[a-zA-Z_]+\":\d+:" \
    "id:100001,\
    phase:2,\
    deny,\
    status:403,\
    msg:'PHP Object Injection attempt blocked',\
    log,\
    severity:CRITICAL"