CVE-2025-54007: Post Grid Plugin Object Injection Flaw

CVE-2025-54007 Overview

CVE-2025-54007 is a PHP Object Injection vulnerability in the PickPlugins Post Grid and Gutenberg Blocks WordPress plugin. The flaw stems from deserialization of untrusted data [CWE-502] and affects all plugin versions up to and including 2.3.11. An authenticated attacker with low privileges can submit crafted serialized payloads that the plugin deserializes, triggering object injection. Successful exploitation can lead to arbitrary code execution, data tampering, or full site compromise when a suitable PHP gadget chain is present in the WordPress environment.

Critical Impact
Authenticated attackers can inject malicious PHP objects through the plugin, potentially achieving remote code execution and full compromise of the underlying WordPress site.

Affected Products

PickPlugins Post Grid and Gutenberg Blocks (plugin slug: post-grid)
All versions from initial release through 2.3.11
WordPress sites with the vulnerable plugin installed and activated

Discovery Timeline

2025-08-20 - CVE-2025-54007 published to NVD
2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-54007

Vulnerability Analysis

The vulnerability resides in the Post Grid and Gutenberg Blocks plugin's handling of user-supplied serialized data. The plugin passes attacker-controlled input to a PHP deserialization routine without validating or restricting the resulting object types. When PHP deserializes the payload, it can instantiate arbitrary classes and invoke magic methods such as __wakeup, __destruct, or __toString. If a gadget chain exists in WordPress core, other plugins, or themes loaded on the site, the attacker can chain these methods to achieve arbitrary file writes, SQL execution, or command execution. The attack requires only low-privilege authenticated access, which lowers the barrier for exploitation in multi-author WordPress deployments.

Root Cause

The root cause is unsafe use of PHP's unserialize() function or equivalent deserialization logic on input that originates from HTTP request parameters. The plugin does not enforce an allowlist of permitted classes through the allowed_classes option and does not validate the structural integrity of the serialized data before processing it.

Attack Vector

The attack vector is network-based and requires authentication at a low privilege level such as Subscriber or Contributor. An attacker submits a crafted serialized PHP object string through a plugin endpoint that accepts grid configuration or metadata. The server deserializes the payload, instantiates attacker-chosen classes, and executes any magic methods triggered during the object lifecycle. Refer to the Patchstack Vulnerability Database Entry for additional technical context.

Detection Methods for CVE-2025-54007

Indicators of Compromise

HTTP POST requests to plugin endpoints containing serialized PHP markers such as O:, a:, or s: followed by class names and length specifiers.
Unexpected PHP files written to wp-content/uploads/ or theme directories after authenticated requests.
New or modified WordPress administrator accounts shortly after access by low-privilege users.
Outbound network connections from the web server to attacker-controlled infrastructure following plugin requests.

Detection Strategies

Inspect web server access logs for requests to Post Grid plugin endpoints containing serialized object signatures in POST bodies or query strings.
Enable PHP error logging and alert on warnings related to unserialize() and __wakeup invocations from plugin code paths.
Deploy a web application firewall rule that blocks request bodies matching PHP serialization patterns targeting the plugin.
Monitor the WordPress options table and post meta for serialized values containing unexpected class references.

Monitoring Recommendations

Track plugin version inventory across WordPress installations and alert on versions at or below 2.3.11.
Correlate authenticated user activity from low-privilege accounts with file system writes on the web host.
Forward WordPress audit logs and PHP error logs to a centralized SIEM for retention and correlation with endpoint telemetry.

How to Mitigate CVE-2025-54007

Immediate Actions Required

Update the Post Grid and Gutenberg Blocks plugin to a version released after 2.3.11 that addresses the deserialization flaw.
Audit WordPress user accounts and remove unused low-privilege users that could be leveraged for exploitation.
Review recent uploads and plugin or theme files for unauthorized modifications since the plugin was installed.
Rotate WordPress administrator credentials and any secrets stored in wp-config.php if compromise is suspected.

Patch Information

Apply the vendor-supplied update for the PickPlugins Post Grid and Gutenberg Blocks plugin. Consult the Patchstack Vulnerability Database Entry for the fixed version and patch references. Verify the upgrade through the WordPress admin Plugins page and confirm the reported version is above 2.3.11.

Workarounds

Deactivate and remove the Post Grid and Gutenberg Blocks plugin until a patched release is verified.
Restrict authenticated access to the WordPress site through IP allowlisting or multi-factor authentication for all roles.
Deploy WAF signatures that block PHP serialization patterns in requests targeting plugin endpoints.
Disable user self-registration in WordPress general settings to reduce the pool of low-privilege attackers.

bash

# Configuration example: disable open registration and enforce WAF logging
wp option update users_can_register 0
wp option update default_role subscriber
# Tail PHP error log for deserialization warnings
tail -f /var/log/php/error.log | grep -E 'unserialize|__wakeup|__destruct'