CVE-2026-66651 in MultiVendorX Plugin
Summary
by MITRE • 08/18/2026
Unauthenticated Broken Access Control in MultiVendorX <= 5.0.14 versions.
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Analysis
by VulDB Data Team • 08/18/2026
The vulnerability identified as an unauthenticated broken access control issue within MultiVendorX versions up to and including 5.0.14 represents a critical failure in the application's authorization logic, allowing attackers to perform actions that should be restricted to authenticated users or specific administrative roles. This type of flaw typically arises when the web application fails to properly verify user permissions before processing requests for sensitive endpoints or functions. In the context of MultiVendorX, which is a WordPress plugin designed to facilitate multi-vendor marketplace operations, such a vulnerability could expose critical business logic and data structures that are intended to be protected from public access. The absence of proper authentication checks means that any individual on the internet can interact with these unprotected interfaces without needing valid credentials, effectively bypassing the security perimeter established by the application's login mechanisms.
From a technical perspective, this flaw aligns closely with CWE-284, which describes Improper Access Control, and specifically relates to situations where access control decisions are not enforced before granting information or resources. It also maps to MITRE ATT&CK technique T1078, Valid Accounts, in the sense that attackers can exploit these misconfigurations to gain unauthorized privileges similar to those of legitimate users, although in this specific case, no account is required at all due to the unauthenticated nature of the flaw. The operational impact of such a vulnerability is severe for e-commerce platforms relying on MultiVendorX. Attackers could potentially manipulate vendor settings, alter product listings, access customer data, or even execute administrative functions depending on the exact endpoint affected. This compromises the confidentiality and integrity of the marketplace's data while also posing significant risks to availability if malicious changes disrupt normal operations.
The exploitation of this vulnerability likely involves crafting specific HTTP requests that target internal API endpoints or AJAX handlers within the plugin codebase which lack sufficient validation checks for user roles or session states. Since MultiVendorX integrates deeply with WordPress core functionalities, an attacker might leverage these unauthenticated paths to escalate privileges further if other vulnerabilities exist in conjunction with this access control failure. The consequences extend beyond immediate data theft; they include reputational damage and potential financial loss due to fraudulent transactions or manipulated pricing structures that could be altered through the exposed administrative capabilities.
Mitigation strategies must prioritize immediate remediation by updating MultiVendorX to a version newer than 5.0.14 where these access control issues have been addressed by the developers. Until an update is applied, administrators should consider implementing web application firewall rules to block suspicious requests targeting known vulnerable endpoints if they can be identified through logging and monitoring efforts. Additionally, enforcing strict input validation and ensuring that all sensitive operations require robust authentication checks are essential steps in preventing similar access control failures. Regular security audits and penetration testing focused on authorization logic are recommended to identify and rectify such flaws before they can be exploited by malicious actors seeking to compromise multi-vendor marketplace infrastructure.