CVE-2025-39356: Foodbakery Sticky Cart Object Injection

CVE-2025-39356 Overview

CVE-2025-39356 is a critical deserialization of untrusted data vulnerability affecting the Chimpstudio Foodbakery Sticky Cart WordPress plugin. This insecure deserialization flaw allows unauthenticated attackers to perform PHP Object Injection attacks, 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 execute arbitrary code, manipulate data, or take complete control of affected WordPress installations running the vulnerable Foodbakery Sticky Cart plugin.

Affected Products

• Foodbakery Sticky Cart plugin versions up to and including 3.2
• WordPress installations using the vulnerable plugin versions
• E-commerce and food ordering sites built with the Foodbakery ecosystem

Discovery Timeline

• 2025-05-19 - CVE-2025-39356 published to NVD
• 2025-05-21 - Last updated in NVD database

Technical Details for CVE-2025-39356

Vulnerability Analysis

This vulnerability falls under CWE-502 (Deserialization of Untrusted Data), a dangerous class of security flaws that occurs when an application deserializes data from an untrusted source without proper validation. In the context of the Foodbakery Sticky Cart plugin, the application processes serialized PHP data that can be manipulated by attackers to inject malicious objects.

PHP Object Injection vulnerabilities are particularly severe in WordPress environments because the platform and its plugins often include classes with magic methods (__wakeup(), __destruct(), __toString()) that can be abused as gadget chains. When a malicious serialized object is deserialized, these magic methods execute automatically, potentially allowing arbitrary code execution.

Root Cause

The root cause of CVE-2025-39356 lies in the plugin's failure to properly validate and sanitize serialized data before processing it through PHP's unserialize() function. The plugin accepts user-controlled input that is passed directly to the deserialization mechanism without implementing safeguards such as:

• Input validation to verify expected data types
• Allowlisting of permitted classes during deserialization
• Use of safer data interchange formats like JSON

This oversight enables attackers to craft malicious serialized payloads that instantiate arbitrary PHP objects with attacker-controlled properties.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can send a specially crafted HTTP request containing a malicious serialized PHP object to the vulnerable endpoint. Upon deserialization, the injected object triggers gadget chain execution, which may lead to:

• Remote code execution through Property Oriented Programming (POP) chains
• File system manipulation (read/write/delete operations)
• Database access and manipulation
• Server-side request forgery (SSRF)
• Complete WordPress site takeover

The attack complexity is low, making this vulnerability accessible to attackers with basic PHP exploitation knowledge. Successful exploitation can result in full compromise of confidentiality, integrity, and availability of the affected system.

Detection Methods for CVE-2025-39356

Indicators of Compromise

• Unusual HTTP POST requests to Foodbakery Sticky Cart plugin endpoints containing serialized PHP data patterns (e.g., O:, a:, s: prefixes)
• Presence of unexpected PHP object serialization strings in web server access logs
• Unauthorized file modifications or new files appearing in the WordPress installation directory
• Suspicious outbound network connections originating from the web server

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in incoming requests
• Monitor WordPress debug logs and PHP error logs for deserialization-related errors or warnings
• Deploy file integrity monitoring (FIM) to detect unauthorized changes to plugin files and WordPress core
• Use runtime application self-protection (RASP) solutions that can identify and block object injection attempts

Monitoring Recommendations

• Enable comprehensive logging for all HTTP requests to WordPress plugin endpoints
• Configure alerting for patterns matching PHP serialized data (O:[0-9]+:" regex patterns) in request bodies
• Monitor for privilege escalation attempts and creation of new administrator accounts
• Review web server processes for spawned child processes that may indicate code execution

How to Mitigate CVE-2025-39356

Immediate Actions Required

• Immediately deactivate and remove the Foodbakery Sticky Cart plugin if running version 3.2 or earlier
• Audit WordPress installations for signs of compromise, including unauthorized users and modified files
• Review web server logs for suspicious activity targeting the vulnerable plugin
• Consider restoring from a known-good backup if compromise is suspected

Patch Information

At the time of publication, organizations should check the Patchstack Vulnerability Report for the latest patch status and updated version information. Until a patched version is available, the plugin should be disabled to prevent exploitation.

Workarounds

• Disable the Foodbakery Sticky Cart plugin until a security patch is released by the vendor
• Implement WAF rules to block requests containing serialized PHP object patterns targeting this plugin
• Restrict access to WordPress admin and plugin endpoints using IP allowlisting where feasible
• Consider using a virtual patching solution to add input validation at the web server level

# Example: Block serialized PHP objects in nginx
# Add to your WordPress site nginx configuration
location ~* /wp-content/plugins/foodbakery-sticky-cart/ {
    # Block requests containing serialized PHP objects
    if ($request_body ~* "O:[0-9]+:") {
        return 403;
    }
}