CVE-2026-12949 in Wishlist Member Plugin
Summary
by MITRE • 08/14/2026
The Wishlist Member plugin for WordPress is vulnerable to Account Takeover via Insufficient Verification of Data Authenticity in versions up to and including 3.34.1. This is due to the wpm_register() function validating the registration cookie only against the GET reg parameter while accepting the POST mergewith and POST wpm_id parameters without verifying that the mergewith user ID references a temporary or incomplete registrant that is bound to the current registration transaction. This makes it possible for unauthenticated attackers to take over any existing WordPress account — including administrator accounts — by supplying an arbitrary user's numeric ID as the mergewith value, which causes wp_update_user() to overwrite the target account's username (additionally written via a direct $wpdb UPDATE), password, email address, first name, and last name with attacker-controlled values, while WordPress password and email change notification emails are explicitly suppressed. When wpm_id references a non-existent membership level, no role key is added to the update payload, causing wp_update_user() to preserve the target user's existing role — including administrator — making full privilege escalation a direct consequence of the takeover.
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Analysis
by VulDB Data Team • 08/14/2026
The Wishlist Member plugin for WordPress presents a critical account takeover vulnerability that stems from insufficient verification of data authenticity within its registration processing mechanism. This vulnerability affects versions up to and including 3.34.1 and operates through a fundamental flaw in how the wpm_register() function handles user registration parameters. The core issue manifests when the function validates the registration cookie exclusively against the GET reg parameter while completely bypassing verification for POST parameters mergewith and wpm_id. This asymmetric validation creates a dangerous attack vector where malicious actors can manipulate the registration flow to target existing WordPress accounts without proper authentication.
The technical exploitation of this vulnerability involves constructing a malicious registration request that includes an arbitrary user ID in the mergewith parameter, effectively allowing attackers to overwrite critical account attributes of any existing user. When the system processes this request, it executes wp_update_user() which modifies the target account's username, password, email address, first name, and last name with attacker-controlled values. The vulnerability is further exacerbated by direct database manipulation through $wpdb UPDATE operations that bypass WordPress's normal user validation procedures. Additionally, the system explicitly suppresses WordPress password and email change notification emails, which removes crucial detection mechanisms that would otherwise alert users to unauthorized account modifications.
The operational impact of this vulnerability extends beyond simple credential theft to full privilege escalation capabilities, particularly when attackers leverage the wpm_id parameter to reference non-existent membership levels. This specific condition causes the system to omit role key updates from the payload, thereby preserving the target user's existing role assignments including administrative privileges. This design flaw means that an attacker who successfully takes over a regular user account can potentially maintain access to administrator-level permissions, creating a direct path for complete system compromise. The vulnerability aligns with CWE-284 Access Control Issues and represents a significant weakness in the plugin's authentication and authorization framework.
From a defensive perspective, this vulnerability demonstrates the critical importance of input validation and parameter verification in web application security. The attack pattern follows typical privilege escalation techniques documented in ATT&CK framework under T1078 Valid Accounts and T1548.001 Account Manipulation. Organizations should immediately update to patched versions of the Wishlist Member plugin, implement additional monitoring for unusual registration patterns, and consider implementing rate limiting on registration endpoints. The vulnerability also highlights the need for comprehensive security testing that includes parameter validation scenarios and the importance of following secure coding practices such as principle of least privilege and input sanitization. System administrators should conduct thorough audits of user account permissions and implement multi-factor authentication to mitigate potential exploitation of similar vulnerabilities in other plugins or core WordPress functionality.