CVE-2025-47683: WP Maintenance Object Injection Vulnerability

CVE-2025-47683 Overview

CVE-2025-47683 is a PHP Object Injection vulnerability in the WP Maintenance plugin for WordPress, developed by Florent Maillefaud. The flaw stems from deserialization of untrusted data [CWE-502] and affects all versions of wp-maintenance up to and including 6.1.9.7. An authenticated attacker holding high-privilege access on a vulnerable WordPress site can inject a crafted serialized PHP object and trigger unsafe deserialization within the plugin.

Critical Impact
Successful exploitation allows object injection that can lead to arbitrary code execution, data tampering, or full site compromise when combined with a suitable POP (Property-Oriented Programming) chain in WordPress core or other installed plugins.

Affected Products

Florent Maillefaud WP Maintenance plugin for WordPress
All versions from initial release through 6.1.9.7
WordPress installations with the wp-maintenance plugin enabled

Discovery Timeline

2025-05-07 - CVE-2025-47683 published to NVD
2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-47683

Vulnerability Analysis

The WP Maintenance plugin passes attacker-influenced input to a PHP deserialization routine without validating the structure or origin of the serialized payload. When unserialize() processes the input, PHP instantiates objects defined in the payload and triggers magic methods such as __wakeup(), __destruct(), or __toString() during object lifecycle events. Attackers chain these magic methods across classes available in the WordPress runtime to reach sensitive sinks. This pattern, known as PHP Object Injection, converts a serialization bug into broader impact including file write, SQL execution, or command execution depending on the available gadget chain.

Root Cause

The root cause is unsafe use of PHP's native unserialize() function against data that an attacker can control. The plugin does not enforce JSON or a signed serialization format, nor does it restrict allowed classes with the allowed_classes option. Because the input crosses a trust boundary without validation, any class loaded by WordPress becomes reachable for gadget chain construction.

Attack Vector

Exploitation requires network access to the WordPress site and an authenticated account with high privileges, such as an administrator or a role granted access to the plugin's settings handlers. The attacker submits a serialized PHP object to the vulnerable parameter exposed by the plugin. The plugin deserializes the payload, instantiates attacker-chosen classes, and executes the resulting gadget chain. Refer to the Patchstack advisory for wp-maintenance 6.1.9.7 for vendor-confirmed technical details.

// Conceptual payload shape - no public PoC available
// Attacker-controlled serialized blob reaches unserialize() inside the plugin
// triggering __wakeup/__destruct on a class chain present in WordPress runtime

Detection Methods for CVE-2025-47683

Indicators of Compromise

HTTP requests to wp-admin endpoints associated with WP Maintenance containing strings such as O: or a: that match PHP serialized object syntax.
Unexpected creation or modification of files under wp-content/uploads/ or plugin directories shortly after authenticated admin activity.
New or modified WordPress administrator accounts, scheduled tasks (wp_cron), or wp_options entries with serialized payloads referencing unfamiliar class names.

Detection Strategies

Inspect web server and application logs for POST requests to WP Maintenance handlers containing PHP serialization tokens (O:\d+:, s:\d+:, __PHP_Incomplete_Class).
Monitor PHP error logs for unserialize() warnings, undefined class notices, or __wakeup errors that often accompany failed object injection attempts.
Run integrity checks against installed plugin files and compare against known-good hashes from the WordPress.org repository.

Monitoring Recommendations

Forward WordPress, web server, and host process telemetry into a centralized data lake such as Singularity Data Lake for correlation across PHP runtime events and endpoint activity.
Alert on PHP processes spawning shells (sh, bash, cmd.exe) or writing to web-accessible paths after requests to the plugin.
Track administrator session anomalies including off-hours logins, new IP geographies, and bulk plugin or theme changes.

How to Mitigate CVE-2025-47683

Immediate Actions Required

Identify all WordPress sites running the wp-maintenance plugin at version 6.1.9.7 or earlier and prioritize them for patching.
Disable the plugin until a fixed version is installed if patching cannot be completed immediately.
Rotate administrator credentials and review recently created users, plugins, and scheduled tasks for signs of abuse.

Patch Information

At the time of NVD publication, the upstream advisory from Patchstack lists versions through 6.1.9.7 as vulnerable. Administrators should upgrade WP Maintenance to the latest available release that addresses object injection and consult the Patchstack vulnerability entry for the fixed version and changelog.

Workarounds

Deactivate and remove the WP Maintenance plugin until an updated, patched release is available.
Restrict administrative access using IP allow-listing, multi-factor authentication, and least-privilege role assignments to reduce the pool of accounts capable of triggering the vulnerable code path.
Deploy a web application firewall rule that blocks request bodies containing PHP serialized object signatures targeting plugin endpoints.

bash

# Example: temporarily deactivate the plugin via WP-CLI on affected hosts
wp plugin deactivate wp-maintenance
wp plugin status wp-maintenance