CVE-2026-15368 in User Profile Builder Plugin
Summary
by MITRE • 08/01/2026
The User Profile Builder WordPress plugin before 3.16.4 does not correctly bind the automatic login performed after user registration to the newly created account, allowing unauthenticated attackers to obtain an authenticated session for an arbitrary existing user, including administrators, on sites using a supported but non-default configuration.
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Analysis
by VulDB Data Team • 08/01/2026
The User Profile Builder WordPress plugin vulnerability stems from a critical flaw in session management during the user registration and automatic login process. This issue affects versions prior to 3.16.4 and represents a serious security regression that undermines the fundamental authentication mechanisms of WordPress installations. The vulnerability specifically manifests when sites utilize supported but non-default configurations, making it particularly concerning for organizations that have customized their WordPress deployment beyond standard defaults. Attackers can exploit this weakness to obtain authenticated sessions for arbitrary existing users, including high-privilege administrator accounts, without requiring valid credentials or knowledge of user passwords.
The technical root cause lies in the improper binding of authentication tokens during the automatic login sequence that occurs immediately following user registration. When a new user registers through the plugin, the system should establish a secure session tied explicitly to the newly created account. However, due to flawed session management logic, the authentication process fails to properly associate the generated session with the correct user identity. This misbinding allows an attacker who can trigger the registration process to manipulate the automatic login mechanism and gain access to existing user accounts rather than being restricted to only creating new ones.
The operational impact of this vulnerability extends far beyond simple privilege escalation. Organizations running affected versions of the User Profile Builder plugin face significant risks including unauthorized administrative access, data breaches, content manipulation, and potential full system compromise. The vulnerability is particularly dangerous because it operates without requiring authentication from the attacker's side, meaning that even unauthenticated users can leverage this flaw to obtain legitimate sessions for existing accounts. This creates a scenario where attackers can impersonate any user in the system, including those with elevated privileges such as administrators, editors, or other roles with substantial access rights.
The weakness aligns with several cybersecurity standards and threat models including CWE-287 which addresses improper authentication issues, and represents a variant of the broader class of session management vulnerabilities that fall under ATT&CK technique T1566 for credential harvesting. The vulnerability also demonstrates characteristics consistent with privilege escalation attacks in the MITRE ATT&CK framework, specifically targeting the privilege escalation phase where attackers seek to gain higher-level access rights. Organizations should consider this issue as a critical security concern requiring immediate attention and remediation.
Mitigation strategies should focus on upgrading to User Profile Builder version 3.16.4 or later, which contains the necessary patches to address the session binding flaw. Additionally, administrators should conduct thorough security audits of their WordPress installations to identify any other plugins or themes that might exhibit similar session management issues. Network monitoring should be enhanced to detect unusual authentication patterns and automated login sequences that could indicate exploitation attempts. Security teams should also consider implementing additional layers of authentication including two-factor authentication and access control measures that can provide defense in depth against such vulnerabilities. Regular vulnerability scanning and penetration testing should be conducted to identify potential similar weaknesses in the WordPress ecosystem and prevent exploitation of related security flaws.