Atomic Edge analysis of CVE-2026-27060 (metadata-based):
This vulnerability affects the ARMember Premium plugin versions up to and including 7.0. It allows authenticated attackers with contributor-level access and above to perform PHP Object Injection via deserialization of untrusted input. The CVSS score is 7.5 (High) with a vector indicating network access, high attack complexity, low privileges required, no user interaction, and a unified High impact on confidentiality, integrity, and availability.
The root cause is a PHP Object Injection vulnerability classified under CWE-502 (Deserialization of Untrusted Data). This occurs when the plugin passes user-supplied serialized data to PHP’s unserialize() function without proper validation or sanitization. Atomic Edge analysis infers that the plugin likely processes serialized input through an AJAX handler or REST endpoint, likely involving user profile updates, membership level settings, or content restriction rule submissions. Since no source code is available, these conclusions are based on the CWE classification and typical WordPress plugin patterns for membership management plugins, which frequently handle complex nested data structures.
Exploitation requires an authenticated user with contributor-level access or higher. The attacker sends a crafted serialized PHP object to a vulnerable endpoint. Likely targets include AJAX actions registered by the plugin, such as armember_save_profile, armember_update_level, or armember_manage_content_restriction. The attacker would POST to /wp-admin/admin-ajax.php with the action parameter set to the vulnerable handler and include a serialized payload in a parameter like data, settings, or options. The payload would be a serialized PHP object that, upon deserialization, triggers a POP (Property Oriented Programming) chain if a suitable gadget exists in an installed plugin or theme. The attacker must first identify or chain gadgets from other available components.
Remediation requires the plugin developer to replace all instances of unserialize() with json_decode() or to implement strict type validation and sanitization of serialized input. The fix should also incorporate nonce verification and capability checks on all AJAX handlers that process complex data structures. Since no patched version is available, users must disable or remove the plugin immediately and migrate to an alternative membership solution.
Impact if exploited: An attacker can achieve arbitrary code execution, delete arbitrary files, or extract sensitive data from the WordPress database, dependent on available POP chains from other plugins or themes. The lack of a known POP chain in the vulnerable software does not reduce risk because attackers commonly install dedicated gadget chains or exploit chains present in other installed components. The high attack complexity in the CVSS likely reflects the requirement for a POP chain, not difficulty in reaching the vulnerable code.
