CVE-2026-94390: Hide Shipping Method PHP Injection Flaw

CVE-2026-94390 Overview

CVE-2026-94390 is a PHP Object Injection vulnerability affecting the Hide Shipping Method For WooCommerce WordPress plugin in versions <= 1.5.4. The flaw stems from insecure deserialization of untrusted input ([CWE-502]) accessible to authenticated users with Editor-level privileges. Successful exploitation allows an attacker to instantiate arbitrary PHP objects, potentially triggering property-oriented programming (POP) chains that lead to code execution, file manipulation, or data compromise within the WordPress environment.

Critical Impact
An authenticated Editor can inject serialized PHP objects into the plugin's input handling, enabling attacks against confidentiality, integrity, and availability of the WooCommerce site.

Affected Products

Hide Shipping Method For WooCommerce plugin versions 1.5.4 and earlier
WordPress sites running WooCommerce with the vulnerable plugin installed
Any environment where the plugin is active and Editor-level accounts exist

Discovery Timeline

2026-10-01 - CVE-2026-94390 published to NVD
2026-10-01 - Last updated in NVD database

Technical Details for CVE-2026-94390

Vulnerability Analysis

The vulnerability resides in input handling that passes attacker-controlled data to a PHP deserialization function such as unserialize(). When PHP deserializes a crafted string, it reconstructs objects and invokes magic methods including __wakeup() and __destruct(). An attacker with Editor privileges can supply a serialized payload referencing classes already loaded within WordPress, WooCommerce, or other active plugins. Chained together, these class gadgets can produce arbitrary file writes, SQL execution, or remote code execution depending on available POP gadgets in the runtime.

The network attack vector requires an authenticated session, but Editor is a common delegated role on multi-author WordPress sites, lowering the practical barrier.

Root Cause

The root cause is improper handling of serialized data within a plugin feature available to Editor users. The plugin deserializes input without validating structure, origin, or type, violating the guidance against passing untrusted input to unserialize(). CWE-502 (Deserialization of Untrusted Data) describes this exact class of flaw.

Attack Vector

An authenticated Editor submits a crafted serialized PHP object through a plugin endpoint. The server deserializes the payload, instantiating attacker-chosen objects. If a suitable POP gadget exists in the WordPress ecosystem loaded on the site, the deserialization triggers arbitrary behavior ranging from file writes to command execution.

No verified public exploit code is available. See the Patchstack Vulnerability Report for additional technical context.

Detection Methods for CVE-2026-94390

Indicators of Compromise

Serialized PHP object patterns such as O: or a: in POST parameters sent to plugin endpoints by Editor accounts
Unexpected PHP files written under wp-content/uploads/ or plugin directories
New administrator accounts, modified wp_options, or altered theme files following Editor activity
Outbound connections from the web server to unknown hosts shortly after plugin requests

Detection Strategies

Inspect web server and WordPress audit logs for POST requests to Hide Shipping Method For WooCommerce endpoints containing serialized object markers
Enable PHP error logging to surface deserialization warnings or unexpected class instantiation
Deploy WAF rules that flag serialized PHP payloads in request bodies and query strings

Monitoring Recommendations

Alert on changes to WordPress core, plugin, and theme files on production hosts
Monitor privilege changes and new user creation events in wp_users and wp_usermeta
Track process creation on the web host, especially PHP spawning shells or network utilities

How to Mitigate CVE-2026-94390

Immediate Actions Required

Update Hide Shipping Method For WooCommerce to a version later than 1.5.4 once a patched release is published by the vendor
Audit all Editor-level accounts and remove or downgrade any that are not required
Rotate passwords for Editor and higher-privileged accounts, and enforce multi-factor authentication
Review file system and database for signs of post-exploitation activity

Patch Information

Refer to the Patchstack Vulnerability Report for current patch status and vendor advisories. Until a fixed version is confirmed, treat all versions <= 1.5.4 as vulnerable.

Workarounds

Deactivate and remove the Hide Shipping Method For WooCommerce plugin until a patched release is available
Restrict access to WordPress administration using IP allowlisting at the web server or WAF layer
Deploy a virtual patch via Patchstack or an equivalent WAF ruleset that blocks serialized PHP payloads to plugin endpoints

bash

# Configuration example: block serialized PHP objects in request bodies with ModSecurity
SecRule REQUEST_URI "@contains /wp-admin/" \
  "id:1026943901,phase:2,deny,status:403,log,\
   msg:'Possible PHP object injection (CVE-2026-94390)',\
   chain"
  SecRule REQUEST_BODY "@rx (?:^|&|=)(?:O|a):\d+:\{" "t:none,t:urlDecode"