CVE-2026-22333: YITH WooCommerce Compare Object Injection

CVE-2026-22333 Overview

A Deserialization of Untrusted Data vulnerability has been identified in the YITH WooCommerce Compare plugin for WordPress. This security flaw allows attackers to exploit Object Injection through insecure deserialization of user-controlled data. The vulnerability affects YITH WooCommerce Compare versions through 3.6.0, potentially allowing malicious actors to inject arbitrary PHP objects into the application.

Critical Impact

This Object Injection vulnerability could allow attackers to execute arbitrary code, manipulate application logic, or access sensitive data by injecting malicious serialized objects into the WordPress application.

Affected Products

• YITH WooCommerce Compare plugin versions up to and including 3.6.0
• WordPress installations using vulnerable YITH WooCommerce Compare versions

Discovery Timeline

• 2026-02-19 - CVE-2026-22333 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-22333

Vulnerability Analysis

This vulnerability stems from insecure deserialization practices within the YITH WooCommerce Compare plugin (CWE-502). When the application deserializes untrusted data without proper validation, it opens the door for Object Injection attacks. In PHP applications like WordPress plugins, this typically occurs when user-supplied input is passed directly to unserialize() functions without adequate sanitization.

Object Injection vulnerabilities in WordPress plugins are particularly dangerous because they can leverage existing classes within the WordPress ecosystem or the plugin itself to construct "POP chains" (Property-Oriented Programming chains). These chains can be used to achieve various malicious outcomes depending on the available gadgets in the codebase.

Root Cause

The root cause of this vulnerability is the deserialization of untrusted data without proper input validation. The YITH WooCommerce Compare plugin processes serialized data from user input without verifying its integrity or origin. When PHP's unserialize() function processes attacker-controlled data, it can instantiate arbitrary objects with attacker-defined properties, potentially triggering dangerous magic methods like __wakeup(), __destruct(), or __toString().

Attack Vector

An attacker can exploit this vulnerability by crafting a malicious serialized payload and submitting it to the vulnerable endpoint within the YITH WooCommerce Compare plugin. The exploitation process typically involves:

1. Identifying the entry point where serialized data is accepted
2. Analyzing the codebase for exploitable classes with dangerous magic methods
3. Constructing a serialized payload that chains these classes together
4. Submitting the malicious payload to trigger the deserialization vulnerability

When deserialized, the malicious object triggers a chain of method calls that can lead to remote code execution, file manipulation, or other security-critical actions. For detailed technical information, refer to the Patchstack security advisory.

Detection Methods for CVE-2026-22333

Indicators of Compromise

• Unusual serialized data patterns in HTTP requests containing O: prefixes indicating PHP objects
• Suspicious POST requests to WooCommerce compare endpoints with encoded payloads
• Unexpected file system changes or new files in WordPress directories
• Anomalous PHP process execution or shell command invocations
• Log entries showing errors related to object instantiation or magic method execution

Detection Strategies

• Monitor web server logs for requests containing serialized PHP object patterns (O:[0-9]+:)
• Implement Web Application Firewall (WAF) rules to detect and block serialized object payloads
• Deploy file integrity monitoring on WordPress installation directories
• Review application logs for deserialization errors or unexpected class instantiation
• Use security plugins that can detect and alert on suspicious plugin behavior

Monitoring Recommendations

• Enable detailed logging for the YITH WooCommerce Compare plugin and WordPress core
• Configure real-time alerting for any detected Object Injection patterns
• Regularly audit POST request bodies for serialized data submissions
• Monitor outbound connections from the web server for signs of compromise

How to Mitigate CVE-2026-22333

Immediate Actions Required

• Update YITH WooCommerce Compare plugin to a version higher than 3.6.0 when available
• Temporarily disable the YITH WooCommerce Compare plugin if immediate update is not possible
• Implement WAF rules to block requests containing serialized PHP objects
• Review recent logs for any signs of exploitation attempts
• Conduct a security audit of WordPress installations using this plugin

Patch Information

Organizations using YITH WooCommerce Compare should check for available updates through the WordPress plugin repository or the vendor's official website. Security updates addressing this deserialization vulnerability should be applied immediately upon release. Refer to the Patchstack vulnerability database for the latest patch information.

Workarounds

• Disable the YITH WooCommerce Compare plugin until a patched version is available
• Implement server-level input filtering to block serialized PHP object patterns in requests
• Use a Web Application Firewall with rules specifically targeting deserialization attacks
• Restrict plugin functionality to authenticated administrative users only
• Consider using alternative WooCommerce comparison plugins that are not affected by this vulnerability

# Configuration example - WAF rule to block serialized PHP objects
# ModSecurity rule to detect PHP object injection attempts
SecRule REQUEST_BODY "@rx O:[0-9]+:\"[a-zA-Z_][a-zA-Z0-9_]*\"" \
    "id:100001,phase:2,deny,status:403,msg:'PHP Object Injection Attempt Detected'"