CVE-2025-26885: WordPress Assistant Object Injection Flaw

CVE-2025-26885 Overview

CVE-2025-26885 is a PHP Object Injection vulnerability in the Beaver Builder WordPress Assistant plugin (assistant). The flaw stems from deserialization of untrusted data [CWE-502] and affects all plugin versions up to and including 1.5.1. An authenticated attacker with high privileges can submit crafted serialized payloads that the plugin unserializes, triggering execution of arbitrary PHP object methods through magic functions. Successful exploitation can lead to remote code execution, data tampering, or full site compromise when suitable gadget chains exist in the WordPress core or installed plugins.

Critical Impact
Authenticated attackers can inject malicious PHP objects through the WordPress Assistant plugin, potentially achieving remote code execution and full compromise of confidentiality, integrity, and availability on the affected WordPress site.

Affected Products

Beaver Builder WordPress Assistant plugin (assistant) versions up to and including 1.5.1
WordPress installations running the vulnerable plugin
Sites with PHP object injection gadget chains available in core or other plugins

Discovery Timeline

2025-03-03 - CVE-2025-26885 published to NVD
2026-04-29 - Last updated in NVD database

Technical Details for CVE-2025-26885

Vulnerability Analysis

The WordPress Assistant plugin passes attacker-controllable input to a PHP deserialization function without validating its source or contents. PHP's unserialize() reconstructs objects defined by the input, automatically invoking magic methods such as __wakeup(), __destruct(), or __toString() on the resulting instances. When suitable gadget classes are loaded in the WordPress environment, an attacker can chain these methods together to perform unintended operations.

The attacker must hold high privileges on the target site to reach the vulnerable code path. However, once reached, the impact spans confidentiality, integrity, and availability because injected objects can read files, modify database records, or execute commands depending on the gadgets available.

The EPSS score is 0.192% (41st percentile), reflecting relatively low observed exploitation activity to date. Refer to the PatchStack WordPress Vulnerability advisory for additional technical context.

Root Cause

The root cause is unsafe deserialization of user-supplied data within the assistant plugin. The plugin invokes unserialize() on input that crosses a trust boundary, violating PHP's documented guidance against deserializing untrusted data. No allow-list or signature verification gates the operation.

Attack Vector

The attack vector is network-based and requires an authenticated session with high privileges. An attacker submits a crafted serialized PHP object string to a vulnerable plugin endpoint or stored field. When the plugin deserializes the payload, PHP instantiates the attacker-controlled object graph and triggers magic methods, enabling exploitation through pre-existing gadget chains. No verified proof-of-concept exploit is publicly available at this time.

Detection Methods for CVE-2025-26885

Indicators of Compromise

Unexpected serialized PHP payloads in HTTP request bodies or query parameters directed at /wp-admin/ endpoints associated with the Assistant plugin
Presence of strings such as O: or a: followed by class names in plugin-related request logs
Newly created administrator accounts, unfamiliar scheduled tasks, or modified PHP files under wp-content/
Outbound network connections from the WordPress server to unfamiliar hosts following plugin requests

Detection Strategies

Inspect web server access logs for requests containing serialized object markers targeting the assistant plugin paths
Monitor WordPress audit logs for high-privilege user actions involving the Assistant plugin
Deploy web application firewall rules that flag serialized PHP payloads in unexpected parameters
Compare installed plugin file hashes against vendor-published versions to identify tampering

Monitoring Recommendations

Forward WordPress, PHP, and web server logs to a centralized SIEM for correlation against authentication anomalies
Alert on file integrity changes within wp-content/plugins/assistant/ and the broader plugin directory
Track creation of new admin users, role escalations, and unscheduled cron entries
Baseline outbound traffic from web servers to detect post-exploitation command-and-control activity

How to Mitigate CVE-2025-26885

Immediate Actions Required

Update the Beaver Builder WordPress Assistant plugin to a version later than 1.5.1 as soon as a fixed release is available
Restrict administrative access to trusted personnel and enforce multi-factor authentication on all privileged accounts
Audit existing administrator and editor accounts for unauthorized additions or privilege changes
Review web server and WordPress logs for serialized payloads received before patching

Patch Information

Consult the PatchStack advisory for the latest patched version and remediation guidance from Beaver Builder. Apply the vendor-provided update through the WordPress plugin management interface or via WP-CLI once available.

Workarounds

Deactivate and remove the assistant plugin until a patched version is installed
Deploy WAF signatures that block PHP serialized object syntax in HTTP requests reaching plugin endpoints
Limit access to /wp-admin/ to known IP addresses through web server or network ACLs
Reduce the number of users holding administrator or editor roles to shrink the attack surface

bash

# Disable the vulnerable plugin via WP-CLI until a patch is applied
wp plugin deactivate assistant
wp plugin delete assistant

# Verify no remaining files reference the plugin
find wp-content/plugins -type d -name assistant