CVE-2025-67619: Kids Heaven Object Injection Vulnerability

CVE-2025-67619 Overview

CVE-2025-67619 is a Deserialization of Untrusted Data vulnerability (CWE-502) affecting the Kids Heaven WordPress theme (kids-world) by designthemes. This vulnerability allows attackers to perform PHP Object Injection attacks against WordPress sites running the affected theme versions.

PHP Object Injection vulnerabilities occur when user-controllable input is passed to PHP's unserialize() function without proper validation. Attackers can craft malicious serialized objects that, when deserialized, can trigger dangerous "magic methods" within the application or its dependencies, potentially leading to remote code execution, file manipulation, or other severe security impacts.

Critical Impact

Successful exploitation of this Object Injection vulnerability could allow attackers to execute arbitrary code, manipulate files, or compromise the underlying WordPress installation and server.

Affected Products

• Kids Heaven WordPress Theme (kids-world) versions through 3.2
• WordPress installations using the affected Kids Heaven theme
• Websites built with designthemes Kids Heaven theme package

Discovery Timeline

• 2026-01-22 - CVE-2025-67619 published to NVD
• 2026-01-22 - Last updated in NVD database

Technical Details for CVE-2025-67619

Vulnerability Analysis

This vulnerability stems from improper handling of serialized data within the Kids Heaven WordPress theme. When PHP applications deserialize untrusted user input, attackers can inject specially crafted serialized objects that exploit the application's class autoloading mechanisms and magic methods such as __wakeup(), __destruct(), or __toString().

In WordPress environments, Object Injection vulnerabilities are particularly dangerous because WordPress themes and plugins often include classes with exploitable magic methods. When these "gadget chains" exist within the codebase, attackers can chain multiple class interactions to achieve arbitrary code execution or other malicious outcomes.

The vulnerability affects all versions of the Kids Heaven theme from the earliest release through version 3.2, indicating a fundamental flaw in how the theme processes serialized data.

Root Cause

The root cause of CVE-2025-67619 is the use of PHP's unserialize() function on untrusted data without proper input validation or sanitization. The Kids Heaven theme fails to adequately verify that serialized data originates from a trusted source before processing it, allowing attackers to inject malicious serialized payloads.

Secure alternatives include using json_encode()/json_decode() for data serialization, implementing allowlists for permitted classes during deserialization (using the allowed_classes option in PHP 7.0+), or avoiding deserialization of user-controlled input entirely.

Attack Vector

The attack vector for this vulnerability involves sending maliciously crafted serialized PHP objects to the WordPress site through user-controllable input channels processed by the Kids Heaven theme. Attackers must identify an entry point where the theme deserializes user input and craft a payload that exploits available gadget chains within WordPress core, the theme itself, or installed plugins.

A typical exploitation scenario involves:

1. Identifying the vulnerable deserialization endpoint within the theme
2. Analyzing available classes for exploitable magic methods (gadget hunting)
3. Constructing a serialized payload that chains gadgets to achieve the desired outcome
4. Submitting the malicious payload through the vulnerable input channel

The exploitation complexity depends on available gadget chains and the specific functionality exposed by the deserialization endpoint. For detailed technical information, see the Patchstack WordPress Vulnerability Report.

Detection Methods for CVE-2025-67619

Indicators of Compromise

• Unusual PHP serialized strings in web server access logs containing class names and property definitions
• Unexpected file modifications or new files created in WordPress directories
• Suspicious outbound network connections from the web server
• Modified WordPress core files or theme files
• New administrator accounts or privilege changes

Detection Strategies

• Monitor web application firewall (WAF) logs for requests containing serialized PHP object patterns (strings starting with O:, a:, s:)
• Implement file integrity monitoring on WordPress installations to detect unauthorized modifications
• Review PHP error logs for deserialization-related warnings or class instantiation errors
• Deploy intrusion detection rules targeting PHP Object Injection attack patterns
• Audit theme and plugin activity logs for anomalous behavior

Monitoring Recommendations

• Enable comprehensive logging for WordPress and the Kids Heaven theme
• Configure real-time alerting for detection of serialized object patterns in request parameters
• Implement endpoint detection and response (EDR) solutions to monitor for post-exploitation activity
• Regularly review user accounts and permissions for unauthorized changes
• Monitor system processes spawned by the web server for suspicious activity

How to Mitigate CVE-2025-67619

Immediate Actions Required

• Update the Kids Heaven theme to a patched version when available from designthemes
• If no patch is available, consider temporarily disabling or replacing the theme
• Implement Web Application Firewall (WAF) rules to block PHP serialized object patterns in requests
• Review WordPress installations for signs of compromise
• Restrict access to WordPress admin interfaces using IP allowlisting or VPN

Patch Information

Organizations using the Kids Heaven theme should check for updates from designthemes and apply any available security patches immediately. Monitor the Patchstack vulnerability database for updated remediation guidance.

If a patched version is not yet available, consider implementing temporary mitigations such as WAF rules or switching to an alternative theme until the vulnerability is addressed.

Workarounds

• Deploy a Web Application Firewall with rules to block requests containing serialized PHP objects
• Implement input validation at the application level to reject serialized data from untrusted sources
• Consider using security plugins that provide virtual patching capabilities for WordPress vulnerabilities
• Restrict file system permissions to limit the impact of potential exploitation
• Regularly backup WordPress installations to enable rapid recovery if compromise occurs

# Example WAF rule for ModSecurity to block PHP serialized objects
SecRule ARGS "@rx [OC]:\d+:\"" \
    "id:1001,\
    phase:2,\
    deny,\
    status:403,\
    msg:'PHP Object Injection Attempt Blocked',\
    log,\
    severity:CRITICAL"