CVE-2026-11966 in User Registration & Membership Plugin
Summary
by MITRE • 07/17/2026
The User Registration & Membership WordPress plugin before 5.2.3 does not perform a capability check for unauthenticated callers on one of its membership payment actions and acts on a caller-supplied user identifier, allowing unauthenticated attackers to delete recently-registered, payment-pending user accounts.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/17/2026
The vulnerability exists within the User Registration & Membership WordPress plugin version 5.2.2 and earlier, where insufficient access control mechanisms fail to validate user privileges before processing membership payment actions. This flaw specifically affects the plugin's handling of user account deletion operations that occur during the payment processing workflow, creating a critical security gap that can be exploited by unauthenticated attackers. The vulnerability stems from the plugin's failure to implement proper capability checks when processing requests containing user identifiers, allowing malicious actors to manipulate the system through crafted requests that target recently created user accounts.
The technical implementation of this vulnerability involves the plugin's payment processing endpoint accepting caller-supplied user identifiers without verifying whether the requesting party possesses appropriate authorization rights. This design flaw creates a path for attackers to construct malicious requests that appear to originate from legitimate payment processing operations while actually targeting user account deletion functions. The vulnerability becomes particularly dangerous because it specifically targets recently-registered accounts that are in a payment-pending state, making it difficult to detect the compromise through normal monitoring procedures. Attackers can exploit this weakness by crafting requests with valid-looking user identifiers and initiating deletion operations against accounts that have been created but not yet fully authenticated or confirmed.
The operational impact of this vulnerability extends beyond simple account deletion, as it represents a significant threat to user data integrity and system security within WordPress environments. Unauthenticated attackers can systematically target newly registered users who have initiated payment processes but have not yet completed authentication, potentially disrupting legitimate user onboarding workflows and causing data loss for users who may have invested time and resources into registration. The vulnerability's exploitation capability becomes particularly concerning in high-traffic environments where numerous accounts are created and processed simultaneously, as it allows attackers to perform coordinated attacks that could result in widespread account purges or systematic disruption of membership services.
This vulnerability aligns with CWE-285, which addresses insufficient authorization checks, and specifically relates to the broader category of access control weaknesses that enable unauthorized privilege escalation. From an adversarial perspective, this flaw provides an attack vector that maps to multiple ATT&CK techniques including privilege escalation through access token manipulation and credential access through exploitation of authentication bypasses. The vulnerability's impact is amplified by the fact that it requires no prior authentication credentials or session information, making it particularly attractive to automated attack tools that can systematically scan for vulnerable WordPress installations. Organizations using this plugin are advised to implement immediate patching procedures, as well as enhanced monitoring for unusual account deletion patterns and unauthorized access attempts.
Mitigation strategies should include immediate deployment of the patched version 5.2.3 or later, along with comprehensive security hardening measures such as implementing rate limiting on membership-related endpoints, conducting regular vulnerability assessments of third-party plugins, and establishing robust monitoring protocols for user account modification activities. Additionally, administrators should consider implementing additional authentication layers for payment processing operations and regularly audit plugin access controls to prevent similar vulnerabilities from emerging in other components of the WordPress ecosystem. The incident highlights the critical importance of proper capability checks in web applications and demonstrates how seemingly minor implementation oversights can result in significant security breaches affecting user data and system integrity.