CVE-2026-66620 in OptionTree Plugin
Summary
by MITRE • 08/18/2026
Editor PHP Object Injection in OptionTree <= 2.7.3 versions.
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Analysis
by VulDB Data Team • 08/18/2026
The vulnerability identified as Editor PHP Object Injection within OptionTree plugin versions prior to or equal to 2.7.3 represents a critical server-side security flaw that allows authenticated attackers to execute arbitrary code on the targeted web application infrastructure. This specific class of vulnerability stems from improper handling of user-supplied input during the deserialization process, where untrusted data is passed directly into PHP functions such as unserialize without adequate validation or sanitization mechanisms in place. In the context of WordPress plugins like OptionTree, which are designed to manage theme options and customizer settings, this flaw provides a direct pathway for remote code execution if an attacker can achieve authentication on the target site.
From a technical perspective, the core issue lies in how the plugin processes data submitted through its editor interface or related administrative endpoints. When a user submits configuration data, the application attempts to deserialize these inputs to reconstruct PHP objects that represent various theme settings. Because the deserialization process does not strictly validate the structure and type of the incoming serialized string, an attacker can craft a malicious payload containing a specially constructed object graph. This crafted input exploits insecure deserialization patterns where the class properties or methods referenced in the serialized data are resolved dynamically by the PHP runtime environment. If the application includes classes that contain magic methods such as __wakeup, __destruct, or __toString, these methods will be invoked automatically during the unserialization process, allowing the attacker to trigger side effects beyond simple object instantiation.
The operational impact of this vulnerability is severe and potentially catastrophic for web applications relying on affected versions of OptionTree. Successful exploitation enables an authenticated user with low privileges, such as a subscriber or contributor role depending on specific plugin configurations, to achieve full remote code execution (RCE) on the server hosting the WordPress instance. This capability allows attackers to read sensitive files containing database credentials and API keys, modify website content, install webshells for persistent access, pivot into internal network segments, and exfiltrate data from connected databases. The severity is further amplified by the widespread adoption of OptionTree in thousands of themes and plugins, meaning that a successful exploit could lead to large-scale compromise across multiple independent websites if they are not promptly updated or patched.
This vulnerability aligns with CWE-502, which describes Deserialization of Untrusted Data, indicating that the application fails to verify the integrity and trustworthiness of data before processing it as executable code structures. Furthermore, from a tactical standpoint within the MITRE ATT&CK framework, this exploit maps directly to T1059 Command and Scripting Interpreter under the Execution technique group, specifically leveraging PHP scripts for remote command execution. It also relates to T1190 Exploit Public-Facing Application if the authentication barrier is bypassed through other means such as credential stuffing or session hijacking, highlighting how this flaw serves as a critical component in broader attack chains aimed at compromising web infrastructure.
Mitigation strategies must prioritize immediate remediation by upgrading OptionTree to version 2.7.4 or later where these deserialization checks have been hardened and input validation is enforced more rigorously. In cases where updating the plugin is not immediately feasible, administrators should restrict access to WordPress administrative areas using strong multi-factor authentication and IP whitelisting to prevent unauthorized users from reaching the vulnerable endpoints. Additionally implementing a Web Application Firewall with rules capable of detecting anomalous serialized data patterns or PHP object injection signatures can provide an additional layer of defense by blocking malicious payloads before they reach the application logic. Regular security audits focusing on input validation practices across all custom code and third-party integrations are essential to prevent similar vulnerabilities from being introduced in future updates or related plugins.