CVE-2026-12256: Avada PHP Object Injection Vulnerability

CVE-2026-12256 Overview

CVE-2026-12256 is a PHP Object Injection vulnerability affecting the Avada WordPress theme in versions up to and including 3.15.3. The flaw stems from insecure deserialization of untrusted input [CWE-502], allowing authenticated users with Contributor-level privileges to inject crafted PHP objects. Successful exploitation can trigger PHP magic methods through existing classes (POP gadgets) loaded by WordPress or its plugins, leading to arbitrary code execution, file manipulation, or sensitive data disclosure. The vulnerability is reachable over the network and requires low privileges with no user interaction.

Critical Impact
An authenticated Contributor can leverage object injection to achieve high-impact compromise of confidentiality, integrity, and availability on affected WordPress sites running Avada <= 3.15.3.

Affected Products

Avada WordPress theme versions <= 3.15.3
WordPress installations using vulnerable Avada builds
Sites permitting Contributor-level accounts on the affected theme

Discovery Timeline

2026-06-17 - CVE-2026-12256 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-12256

Vulnerability Analysis

The vulnerability resides in the Avada theme's handling of serialized PHP data. The theme passes attacker-controllable input to a deserialization routine without validating that the data originates from a trusted source. When PHP processes the serialized payload, it instantiates objects and may invoke magic methods such as __wakeup, __destruct, or __toString on those objects. If a class with exploitable side effects is loaded in the WordPress runtime, an attacker can chain these methods into a property-oriented programming (POP) gadget to perform unintended actions. These actions can include writing files, executing system commands through cascading method calls, or exfiltrating database contents.

The EPSS score is 0.482% with a percentile of 37.765, indicating limited current exploitation prediction. However, PHP object injection vulnerabilities are well understood and frequently weaponized once public gadget chains exist.

Root Cause

The root cause is insecure deserialization [CWE-502]. The Avada theme calls unserialize() on data influenced by an authenticated Contributor without filtering allowed classes or validating payload integrity through a signature.

Attack Vector

Exploitation requires an account with at least Contributor privileges on the target WordPress site. The attacker submits a crafted serialized payload through a theme-exposed input field or parameter. The payload is deserialized server-side, triggering a gadget chain in loaded code. Refer to the Patchstack WordPress Vulnerability advisory for technical details specific to the affected sinks in Avada.

Detection Methods for CVE-2026-12256

Indicators of Compromise

Unexpected serialized PHP strings (beginning with O:, a:, or s:) submitted in POST bodies or query parameters to Avada theme endpoints.
Newly created administrator accounts or modified user roles following Contributor account activity.
Unexpected PHP files written under wp-content/uploads/ or theme directories.
Outbound network connections originating from the PHP worker process to attacker-controlled hosts.

Detection Strategies

Inspect web server and WordPress audit logs for Contributor-authenticated requests containing serialized object signatures.
Monitor file integrity on wp-content/themes/Avada/ and the broader WordPress install for unauthorized modifications.
Deploy WAF rules that flag PHP serialization patterns in requests to theme handlers.
Correlate Contributor login events with subsequent privilege changes or file writes.

Monitoring Recommendations

Enable verbose logging of POST parameters to Avada theme AJAX endpoints.
Track creation of new PHP files in writable WordPress directories in near real time.
Alert on unserialize() errors and PHP warnings logged by the application.
Review accounts with Contributor or higher privileges for unexpected activity or stale credentials.

How to Mitigate CVE-2026-12256

Immediate Actions Required

Update the Avada theme to a version later than 3.15.3 as published by the vendor.
Audit and disable Contributor accounts that are not actively required.
Rotate WordPress secret keys and salts in wp-config.php after patching.
Review recent posts, uploads, and user changes for signs of exploitation.

Patch Information

Apply the vendor-released Avada theme update that addresses CVE-2026-12256. See the Patchstack WordPress Vulnerability advisory for fixed version guidance and remediation details.

Workarounds

Restrict Contributor account creation and require strong authentication for low-privilege roles.
Place a web application firewall in front of WordPress with rules blocking PHP serialized payloads in untrusted parameters.
Temporarily remove or disable affected Avada features that accept user-supplied serialized data until patching is complete.
Enforce least-privilege file permissions on wp-content/ to limit the impact of arbitrary write gadgets.

bash

# Configuration example: block PHP serialized payloads at the WAF/Nginx layer
if ($request_body ~* "(^|&|=)O:[0-9]+:\"[A-Za-z0-9_\\\\]+\":[0-9]+:\{") {
    return 403;
}