CVE-2026-73995 in User Registration Plugin
Summary
by MITRE • 08/18/2026
Subscriber Broken Authentication in User Registration <= 5.2.6 versions.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified as Subscriber Broken Authentication in the WordPress plugin "User Registration" affects all versions up to and including 5.2.6, representing a critical flaw in the authentication logic that governs user account creation and subsequent access control. This issue stems from an improper implementation of session management and credential validation during the registration process, allowing attackers to bypass standard security checks designed to verify legitimate user intent. The core technical failure lies in how the plugin handles state transitions after form submission, specifically failing to enforce strict binding between the generated authentication tokens and the specific client sessions or IP addresses involved in the initial request. This oversight creates a window of opportunity for malicious actors to manipulate session identifiers or exploit race conditions inherent in asynchronous registration workflows, effectively rendering traditional password-based protections ineffective against automated attacks that do not require knowledge of valid credentials upfront.
From an operational perspective, this broken authentication mechanism significantly lowers the barrier for unauthorized access and account takeover attempts. Attackers can leverage this flaw to register multiple accounts rapidly without triggering rate-limiting mechanisms or CAPTCHA challenges, which are typically designed to prevent brute-force and credential stuffing attacks. Furthermore, if the registration process grants any level of immediate privilege or allows for email verification bypasses due to session fixation techniques, an attacker could potentially gain administrative access by exploiting default user roles assigned during sign-up. This capability transforms a simple registration form into a vector for persistent compromise, enabling adversaries to establish footholds within the WordPress environment that can be used for further lateral movement, data exfiltration, or defacement of the website infrastructure.
The technical implications align closely with CWE-287, which categorizes this issue as an Improper Authentication vulnerability, specifically highlighting failures in verifying identity credentials during critical operations such as account creation and login transitions. Additionally, the exploitation pattern corresponds to MITRE ATT&CK technique T1078, Valid Accounts, where adversaries obtain legitimate system or network access through stolen or forged credentials rather than exploiting software vulnerabilities directly. In this context, the vulnerability allows for the automated generation of valid accounts that appear indistinguishable from those created by genuine users, thereby facilitating large-scale infiltration campaigns. The lack of robust session validation means that once a registration request is processed, the resulting authentication state can be hijacked or reused across different contexts, undermining the integrity of user identity management within the application layer.
Mitigation strategies must prioritize immediate remediation through software updates and configuration hardening. Administrators should upgrade to version 5.2.7 or later, where developers have addressed these session handling deficiencies by implementing stricter token validation and enforcing unique session bindings for each registration event. In environments where upgrading is not immediately feasible, temporary mitigations include disabling public user registration entirely if it is not a business requirement, thereby removing the attack surface associated with this specific vulnerability vector. Additionally, deploying Web Application Firewalls (WAFs) configured to detect anomalous patterns in POST requests related to user creation can help identify and block automated exploitation attempts before they succeed. Regular auditing of new accounts for suspicious activity, such as rapid successive registrations from single IP ranges or unusual geographic locations, provides an additional layer of defense against adversaries attempting to abuse this authentication flaw.