CVE-2026-80467 in Advanced Custom Fields Extended Plugin
Summary
by MITRE • 09/02/2026
The Advanced Custom Fields: Extended WordPress plugin before 0.9.2.7 does not restrict the role submitted through its front-end user forms to the roles the form actually offers, and its safeguard against privileged roles is incomplete, allowing unauthenticated visitors to register an account with elevated capabilities and then escalate it to administrator.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in Advanced Custom Fields: Extended prior to version 0.9.2.7 represents a critical authentication bypass and privilege escalation flaw within the WordPress ecosystem. This plugin facilitates complex form handling on the front end, allowing site administrators to create user registration forms with specific role assignments. However, the underlying implementation fails to enforce server-side validation of the submitted role data against the configuration defined by the administrator. Instead of strictly adhering to a whitelist of permitted roles associated with each specific form instance, the application accepts any role string provided in the HTTP request payload from the client side. This architectural oversight creates a direct path for unauthenticated attackers to manipulate account creation processes and assign themselves administrative privileges without possessing valid credentials or proper authorization.
From a technical perspective, this flaw is classified as CWE-269 Improper Privilege Management combined with CWE-749 Exposure of Dangerous Method or Function in the context of insecure configuration validation. The core issue lies in the lack of robust input sanitization and authority verification during the user registration workflow. When an unauthenticated visitor submits a form, the backend logic processes the role parameter without cross-referencing it against the allowed roles configured for that specific form template. Consequently, if an attacker modifies the request to include a high-privilege role such as administrator or editor, the system accepts this input and provisions the new user account with those elevated capabilities. This bypasses standard WordPress security mechanisms designed to prevent unauthorized privilege assignment, effectively rendering client-side restrictions meaningless since they can be trivially circumvented using tools like curl or browser developer consoles.
The operational impact of this vulnerability is severe, as it allows for complete compromise of the affected WordPress installation. Once an attacker successfully registers a user account with administrator privileges through this flaw, they gain full control over the website's backend interface. This includes the ability to install malicious plugins, modify theme files, access sensitive database information, and execute arbitrary code depending on existing server configurations. The presence of such a vulnerability significantly lowers the barrier for entry for automated scanning bots and opportunistic attackers who routinely probe WordPress sites for registration forms with weak validation logic. It undermines the fundamental security principle that user roles must be assigned based on verified administrative decisions rather than client-supplied data, thereby exposing organizations to potential defacement, data breaches, and use of their infrastructure for further malicious activities such as distributed denial-of-service attacks or phishing campaigns.
Mitigation strategies require immediate action by site administrators who have not yet updated the plugin. The primary remediation is upgrading Advanced Custom Fields: Extended to version 0.9.2.7 or later, where these validation checks have been corrected to ensure that only roles explicitly defined in the form settings can be assigned during registration. In addition to updating software, organizations should implement defense-in-depth measures such as using Web Application Firewalls to monitor and block anomalous user creation requests containing unexpected role parameters. It is also advisable to review existing user accounts for any unauthorized administrators created prior to patching and remove them immediately. Furthermore, adhering to the principle of least privilege by restricting access to wp-admin endpoints via IP whitelisting or two-factor authentication can provide an additional layer of security against potential exploitation attempts while patches are being applied across the infrastructure.