Description

Unauthenticated Broken Authentication in User Registration & Membership Pro <= 5.4.5 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-08-20T12:16:36.940Z",
  "pubdate": "2026-08-20T12:16:36.940Z",
  "executiveSummary": "An unauthenticated broken authentication vulnerability has been identified in the User Registration & Membership Pro plugin affecting versions 5.4.5 and prior. This security flaw introduces severe risk implications by allowing unauthenticated remote threat actors to bypass standard authentication mechanisms during user registration and membership processes. The primary impact of successful exploitation includes unauthorized access to application functionality, potential account takeover, and unauthorized privilege escalation within the affected system. The vulnerability stems from improper handling of authentication controls within the vulnerable component, requiring no prior privileges or user interaction for successful exploitation. Attackers can leverage network exposure to interact directly with the registration endpoint, submitting crafted requests that exploit the flawed authentication logic. Given the critical nature of broken authentication vulnerabilities, organizations utilizing the impacted product face significant exposure to unauthorized data access and system compromise. Immediate remediation is strongly advised to neutralize the threat and secure affected authentication workflows against malicious exploitation.",
  "technicalDetails": "The vulnerability resides within the User Registration & Membership Pro plugin for versions 5.4.5 and below, specifically targeting the user registration and membership management components. The root cause of the issue is a failure in the authentication state validation and session handling logic during the registration flow, which improperly permits unauthenticated entities to execute privileged actions or bypass verification steps normally restricted to authenticated users. Attackers leverage network exposure by sending malicious HTTP requests directly to the vulnerable application endpoints associated with the User Registration & Membership Pro plugin. The attack flow begins with the adversary crafting a specialized payload designed to exploit the absence of strict access controls within the registration function. Because the application fails to validate the authenticity or session state of the requester, the payload is processed as a legitimate operation. Consequently, the attacker can manipulate user accounts, register unauthorized administrative profiles, or bypass multi-factor and standard credential checks. The vulnerability requires no authentication requirements or privilege requirements, enabling low-complexity remote exploitation over the network. The post-exploitation impact includes full compromise of user integrity, unauthorized access to restricted membership areas, and potential lateral movement within the application ecosystem. Detailed analysis of the vulnerable component reveals that insufficient input validation and a lack of cryptographic or session-based verification tokens at critical execution boundaries allow the request to bypass intended security gates. Remediating this flaw requires comprehensive hardening of the authentication state machine, rigorous verification of user privileges prior to executing registration logic, and the implementation of strict access control lists across all associated API endpoints and handler functions."
}