CVE-2026-16030 in MStore API Plugin
Summary
by MITRE • 08/07/2026
The MStore API WordPress plugin before 4.21.0 does not correctly verify the cryptographic signature of the token used to authenticate its phone-based login, allowing unauthenticated attackers who know a registered user's phone number to forge a token and take over that user's account, including administrator accounts.
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Analysis
by VulDB Data Team • 08/07/2026
The vulnerability in the MStore API WordPress plugin affects versions prior to 4.21.0 and represents a critical authentication bypass flaw that undermines the security of phone-based login mechanisms. This issue stems from inadequate cryptographic signature verification during the token authentication process, creating a pathway for unauthorized actors to compromise user accounts through simple social engineering or information gathering techniques. The vulnerability specifically targets the token validation mechanism used in the plugin's phone-based authentication system, where attackers with knowledge of a registered user's phone number can generate forged tokens that appear legitimate to the system.
The technical flaw manifests in the plugin's failure to properly validate cryptographic signatures associated with authentication tokens used for phone-based login processes. This weakness allows attackers to exploit the lack of proper signature verification by crafting malicious tokens that bypass the intended security controls. The vulnerability operates at the authentication layer and leverages a classic cryptographic weakness where the system accepts tokens without sufficient validation of their authenticity, effectively creating a backdoor for account takeover. This flaw is particularly dangerous because it requires minimal prerequisites - simply knowing a registered user's phone number enables an attacker to forge valid authentication tokens.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it specifically targets the phone-based login functionality that many users rely on for secure authentication. Attackers can exploit this weakness to gain access to any account associated with a known phone number, including high-privilege administrator accounts that may control entire WordPress installations. This creates significant risk for organizations where administrators have elevated privileges and sensitive data access. The vulnerability also impacts user trust in the authentication system, as it demonstrates a fundamental breakdown in the security controls designed to protect user accounts from unauthorized access attempts.
The flaw aligns with common security patterns identified in CWE categories related to authentication bypass vulnerabilities and cryptographic weakness. This issue demonstrates poor implementation of token-based authentication mechanisms and highlights the importance of proper cryptographic validation in security-critical components. Organizations using affected versions of the MStore API plugin face potential data breaches, unauthorized modifications to WordPress content, and complete account takeovers that could lead to further compromise of web applications and associated systems. The vulnerability also represents a failure in the principle of least privilege, as successful exploitation allows attackers to elevate their access level beyond normal user boundaries.
Mitigation strategies include immediate upgrade to MStore API plugin version 4.21.0 or later, which contains the necessary cryptographic signature verification fixes. Administrators should also implement additional security measures such as multi-factor authentication for critical accounts, monitoring for unusual login patterns, and regular security audits of WordPress plugins and themes. The vulnerability underscores the importance of proper cryptographic implementation in authentication systems and serves as a reminder that even seemingly simple security controls require robust validation mechanisms to prevent exploitation. Organizations should also consider implementing rate limiting and account lockout mechanisms to further reduce the attack surface and prevent automated exploitation attempts.