CVE-2026-75823 in User Frontend Plugin
Summary
by MITRE • 09/30/2026
The User Frontend WordPress plugin before 4.3.12 does not prevent tampering with the role assigned by its registration form, allowing unauthenticated users to register with a higher privileged role, such as Editor.
This affects installations running a PHP build where the sodium extension is unavailable, and where a registration page has been configured. The administrator role cannot be obtained this way.
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Analysis
by VulDB Data Team • 09/30/2026
The User Frontend WordPress plugin prior to version 4.3.12 contains a critical security vulnerability related to insecure direct object references and broken access control mechanisms within its user registration workflow. This flaw specifically impacts installations where the PHP environment lacks the sodium extension, which is typically used for secure cryptographic operations such as password hashing or token generation. In these specific environments, the plugin fails to properly validate or sanitize the role parameter submitted via the registration form. Consequently, an unauthenticated attacker can manipulate the HTTP request payload to assign a higher privileged user role, such as Editor, during the account creation process. This vulnerability arises because the application relies on client-side input for determining administrative privileges without sufficient server-side verification against authorized roles or proper cryptographic binding that would prevent tampering in environments lacking modern encryption libraries.
From an operational perspective, this vulnerability allows unauthenticated users to escalate their privileges immediately upon registration. By registering with elevated permissions like Editor, attackers gain the ability to manage posts, modify content, and potentially access other administrative features depending on the specific capabilities assigned to that role within the WordPress configuration. This undermines the fundamental security principle of least privilege and compromises the integrity of the website's content management system. The restriction preventing the acquisition of the Administrator role suggests that there are some hardcoded limits or additional checks for the highest level of privilege, but the ability to obtain Editor-level access is sufficient to cause significant damage, including defacement, data exfiltration through accessible media libraries, and further exploitation vectors such as cross-site scripting using elevated capabilities.
This issue aligns with CWE-269 Improper Privilege Assignment and CWE-862 Missing Authorization, reflecting a failure in the application logic to enforce appropriate access controls during user registration. In terms of the MITRE ATT&CK framework, this vulnerability facilitates Initial Access through compromised credentials or account creation (T1078) and potentially leads to Persistence if the attacker can maintain their elevated status. It also relates to Privilege Escalation techniques where an actor gains higher-level permissions than intended by exploiting misconfigured access control mechanisms. The dependency on the absence of the sodium extension highlights a broader issue regarding fallback security measures; when primary cryptographic safeguards are unavailable, secondary validation steps must be robust enough to prevent manipulation, which was not the case in versions prior to 4.3.12.
To mitigate this vulnerability, site administrators should immediately update the User Frontend plugin to version 4.3.12 or later, where these input validation and role assignment checks have been corrected. For environments unable to upgrade due to compatibility constraints, it is advisable to ensure that the PHP sodium extension is enabled if possible, as its presence restores the intended security controls for handling registration data securely. Additionally, implementing a Web Application Firewall can help detect and block attempts to manipulate form parameters associated with user roles during the registration process. Regular auditing of user accounts and monitoring for unusual privilege assignments can also aid in early detection of exploitation attempts stemming from this flaw.