CVE-2025-23944: WOOEXIM Object Injection Vulnerability

CVE-2025-23944 Overview

CVE-2025-23944 is a PHP Object Injection vulnerability affecting the WOOEXIM WordPress plugin developed by bulktheme. The flaw stems from insecure deserialization of untrusted data [CWE-502] in plugin versions up to and including 5.0.0. Authenticated attackers with low privileges can submit crafted serialized payloads over the network to trigger object injection. Successful exploitation can lead to arbitrary code execution, data tampering, or full compromise of the WordPress site. The vulnerability was published to the National Vulnerability Database (NVD) on January 22, 2025.

Critical Impact
Authenticated attackers can exploit deserialization of untrusted data in WOOEXIM ≤ 5.0.0 to inject PHP objects and potentially execute arbitrary code on affected WordPress installations.

Affected Products

bulktheme WOOEXIM WordPress plugin
All versions from n/a through 5.0.0
WordPress installations running the vulnerable plugin

Discovery Timeline

2025-01-22 - CVE-2025-23944 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-23944

Vulnerability Analysis

The vulnerability is classified as Deserialization of Untrusted Data [CWE-502], commonly known as PHP Object Injection. WOOEXIM processes attacker-controlled serialized input without validating its structure or origin. When PHP's unserialize() function reconstructs objects from this input, it instantiates arbitrary classes and invokes magic methods such as __wakeup() and __destruct().

If gadget chains exist within loaded plugins, themes, or the WordPress core, an attacker can chain these class methods to achieve outcomes ranging from file writes to remote code execution. The attack requires network access and low-privilege authentication, but no user interaction. Impact spans confidentiality, integrity, and availability.

Root Cause

The root cause is the plugin's use of PHP deserialization on untrusted input without integrity checks or type filtering. Modern secure coding practice requires replacing unserialize() with json_decode() for external data or using allowed_classes => false to restrict object instantiation. WOOEXIM ≤ 5.0.0 does not implement these safeguards.

Attack Vector

An authenticated user with low privileges submits a crafted serialized payload to a plugin endpoint that accepts it. The payload defines PHP object properties designed to trigger gadget chains during deserialization. Refer to the Patchstack Vulnerability Report for additional technical context.

Detection Methods for CVE-2025-23944

Indicators of Compromise

HTTP requests to WOOEXIM plugin endpoints containing serialized PHP payloads matching patterns like O:, a:, or s: followed by class names and property definitions
Unexpected PHP processes spawning shell commands originating from the wp-content/plugins/wooexim/ directory
New or modified PHP files within the WordPress installation following requests to WOOEXIM endpoints
Outbound network connections initiated by the web server process to unknown hosts after plugin interactions

Detection Strategies

Inspect web server access logs for POST or GET parameters containing serialized PHP object markers targeting WOOEXIM routes
Deploy a Web Application Firewall (WAF) rule to flag serialized object patterns in requests to the affected plugin
Monitor file integrity across wp-content/plugins/ and wp-content/uploads/ for unauthorized modifications
Correlate authentication events with subsequent plugin interactions to identify low-privilege accounts probing WOOEXIM endpoints

Monitoring Recommendations

Enable verbose PHP error logging to capture deserialization failures and unexpected class instantiation
Alert on process execution chains where php-fpm or apache spawn interpreters such as sh, bash, or python
Track outbound connections from web-tier hosts and baseline expected destinations
Retain WordPress audit logs covering user role changes, plugin option updates, and file uploads

How to Mitigate CVE-2025-23944

Immediate Actions Required

Identify all WordPress sites running WOOEXIM and inventory the installed version
Update WOOEXIM to a version above 5.0.0 once the vendor releases a fix, per the Patchstack advisory
Restrict access to WordPress authenticated endpoints and enforce least-privilege role assignments
Rotate credentials for any low-privilege accounts that may have interacted with the vulnerable plugin

Patch Information

At the time of NVD publication, the advisory lists all versions through 5.0.0 as affected. Administrators should consult the Patchstack Vulnerability Report for updated patch availability and apply vendor-supplied updates as soon as they are released.

Workarounds

Disable and remove the WOOEXIM plugin until a patched version is available
Deploy WAF rules that block serialized PHP object markers such as O: and a: in request bodies targeting plugin URLs
Restrict WordPress administrative and subscriber-tier endpoints to trusted IP ranges using web server ACLs
Enforce multi-factor authentication (MFA) for all WordPress accounts to reduce the risk of low-privilege credential abuse

bash

# Example nginx rule to block serialized PHP payloads to WOOEXIM endpoints
location ~* /wp-content/plugins/wooexim/ {
    if ($request_body ~* "(O|a|s):[0-9]+:\"") {
        return 403;
    }
}