Description

Incorrect Privilege Assignment vulnerability in Ultimate Member Ultimate Member ultimate-member allows Privilege Escalation.This issue affects Ultimate Member: from n/a through 2.13.1.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.6",
  "pubDate": "2026-10-09T10:16:45.280Z",
  "pubdate": "2026-10-09T10:16:45.280Z",
  "executiveSummary": "An Incorrect Privilege Assignment vulnerability has been identified within the Ultimate Member WordPress plugin, specifically designated as ultimate-member, affecting all versions from n/a through 2.13.1. This high-severity vulnerability facilitates unauthorized privilege escalation, allowing actors to elevate their access rights within the target WordPress environment.\nThe Ultimate Member plugin is widely utilized for creating advanced user communities, custom registration forms, and comprehensive profile directories, making it a high-value target for malicious actors. By exploiting the underlying flaw in how the plugin assigns and validates user roles during key operations such as user registration, updates, or metadata manipulation, attackers can bypass intended access controls.\nSuccessful exploitation enables low-privileged users, or potentially unauthenticated registration actors, to assign themselves highly privileged roles, such as Administrator. This compromise grants the attacker complete administrative control over the affected WordPress site, enabling them to alter system configurations, access sensitive user databases, inject malicious payloads, and compromise the integrity of the host server. The lack of strict server-side validation on role assignment parameters is the primary driver of this security risk.",
  "technicalDetails": "The core of this vulnerability lies in the incorrect privilege assignment mechanism implemented within the Ultimate Member plugin (ultimate-member) codebase. In affected versions from n/a through 2.13.1, the plugin fails to properly restrict, sanitize, and validate user-supplied input during administrative operations, registration processes, or profile modifications. Consequently, the input validation logic is bypassed by submitting manipulated parameters.\nSpecifically, when a user registers or updates their profile, the application processes request parameters containing user meta keys or role designations. Because the plugin does not enforce strict access control lists (ACLs) or perform adequate server-side verification of the submitted roles, it allows client-controlled data to define the user's role assignment. This allows parameters traditionally reserved for administrative configurations, such as 'wp_capabilities', 'role', or custom Ultimate Member role fields, to be altered via malicious HTTP requests, tricking the database-update mechanism into processing unauthorized role associations.\nAn attack flow targeting this vulnerability typically begins with an attacker mapping the active registration or profile update endpoints exposed by the Ultimate Member plugin. The attacker crafts an HTTP POST request targeting these endpoints, incorporating modified payload parameters designed to manipulate the user metadata directly. For example, the attacker can append parameters like 'role' or custom meta fields associated with the WordPress capability system (such as mapping to the administrator role) to their registration request, bypassing client-side validation mechanisms entirely.\nSince the backend application lacks robust authorization checks to ensure that only authorized administrators can assign administrative roles, the server processes the payload and updates the database with the attacker's requested high-privilege configuration. This results in the target user account being instantiated with elevated administrative privileges immediately upon registration or profile update, granting them immediate, authorized access to security-sensitive administrative views.\nThe post-exploitation impact of this vulnerability is catastrophic for the affected WordPress instance. Upon successfully elevating their privileges to an administrator level, the attacker gains unrestricted access to the WordPress administrative dashboard (wp-admin). From this position of privilege, the attacker can install malicious plugins, upload web shells to achieve remote code execution (RCE) on the underlying hosting server, modify existing site content, extract sensitive database information containing user credentials, or execute arbitrary database queries. Given that the affected version range spans from n/a through 2.13.1, any deployment utilizing these versions without the appropriate security updates remains highly vulnerable to remote exploitation. The exposure is exacerbated because these endpoints are typically exposed to the public network to facilitate standard user registrations, removing the requirement for prior authentication to initiate the exploit."
}