CVE-2026-12497 in Paid Membership Plugin
Summary
by MITRE • 07/24/2026
The Paid Membership Plugin, Ecommerce, User Registration Form, Login Form, User Profile & Restrict Content WordPress plugin before 4.16.18 does not consistently enforce the role restriction configured on its front-end registration role-selection field. The set of roles offered to the visitor and the set of roles the registration handler accepts are derived by two different parsers, and for some valid ways of configuring the offered roles the handler ignores the restriction and falls back to accepting any non-administrator role. Combined with the absence of a nonce on the public registration handler, this allows an unauthenticated visitor to register an account with a higher role, such as Editor or Author, than the form was configured to offer.
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Analysis
by VulDB Data Team • 07/24/2026
The vulnerability in question affects the Paid Membership Plugin for WordPress, specifically version 4.16.18 and earlier, which provides ecommerce functionality along with user registration, login, profile management, and content restriction capabilities. This issue represents a critical access control flaw that undermines the plugin's intended role-based security model through inconsistent parsing mechanisms between frontend role selection and backend validation processes. The vulnerability stems from a fundamental architectural weakness where the plugin employs two separate parsers to handle role configuration - one for presenting available roles to visitors during registration and another for validating incoming registration requests. This dual-parser approach creates a scenario where legitimate configuration options in the frontend interface can result in unexpected behavior in the backend validation logic, effectively bypassing the intended role restrictions.
The technical implementation flaw manifests when administrators configure the plugin's registration form to offer specific user roles such as subscriber or contributor, but due to differences in how the two parsers interpret role definitions, the backend registration handler fails to properly enforce these constraints. The system falls back to accepting any non-administrator role rather than strictly validating against the configured options, creating an arbitrary privilege escalation vector. This issue is compounded by the complete absence of nonce verification on the public registration endpoint, which means that unauthenticated attackers can submit crafted registration requests without proper authentication tokens. According to the CWE database, this vulnerability maps directly to CWE-285: Improper Authorization and CWE-347: Improper Verification of Cryptographic Signature, as it involves both unauthorized access and lack of proper validation mechanisms. The ATT&CK framework categorizes this under T1078: Valid Accounts and T1496: Resource Hijacking, since successful exploitation allows attackers to obtain accounts with elevated privileges that can be used for further compromise.
The operational impact of this vulnerability is substantial as it enables attackers to register accounts with roles such as Editor or Author, which typically possess significant administrative capabilities within WordPress systems. These elevated roles allow unauthorized users to modify content, create posts, and potentially access sensitive areas of the website that should remain restricted. The absence of nonce protection removes any barrier to automated exploitation, making this vulnerability particularly dangerous in environments where the plugin is widely used. Security researchers have noted that such role escalation vulnerabilities frequently lead to full system compromise when combined with other weaknesses, as attackers can leverage these elevated privileges to gain deeper access to server resources, modify critical website components, or establish persistent backdoors.
Mitigation strategies for this vulnerability should begin with immediate patching to version 4.16.18 or later, which addresses the inconsistent parsing logic and implements proper nonce validation on registration endpoints. Administrators should also review all existing user accounts to identify any potentially compromised elevated privileges that may have been gained through exploitation of this vulnerability. Additional defensive measures include implementing rate limiting on registration endpoints to prevent automated exploitation attempts, monitoring for unusual registration patterns that might indicate abuse, and ensuring that role assignment configurations are thoroughly tested in staging environments before deployment to production systems. The vulnerability highlights the importance of consistent input validation and proper authentication mechanisms in web applications, particularly those handling user account creation and privilege management. Organizations should also consider implementing additional layers of security such as CAPTCHA verification on registration forms and regular security audits of third-party plugins to identify similar inconsistencies that could lead to privilege escalation attacks.