CVE-2026-84756 in WCFM Membership Plugin
Summary
by MITRE • 09/03/2026
Subscriber Privilege Escalation in WCFM Membership <= 2.11.11 versions.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability identified as Subscriber Privilege Escalation in the WCMp (WooCommerce Multi Vendor) Membership plugin, specifically affecting versions up to and including 2.11.11, represents a critical security flaw within WordPress-based e-commerce ecosystems that rely on multi-vendor architectures. This issue stems from insufficient access control mechanisms embedded within the plugin's administrative interface and API endpoints. In these affected versions, the software fails to properly verify whether the user initiating an action possesses the necessary elevated privileges before executing sensitive operations related to membership tiers, vendor approvals, or subscription management. Consequently, a low-privileged user account, such as one assigned only Subscriber status in WordPress, can manipulate requests to perform actions that are strictly reserved for administrators or higher-level roles like Shop Managers. This breakdown in authorization logic allows attackers to bypass standard security boundaries designed to isolate regular users from administrative functions.
From a technical perspective, the flaw typically manifests through insecure direct object references or missing function-level access controls within the plugin's PHP codebase. When a Subscriber attempts to interact with endpoints responsible for modifying membership settings, approving vendor applications, or changing product visibility rules, the application does not adequately check the current user’s role against required capabilities defined by WordPress core functions such as current_user_can. This oversight enables the attacker to send crafted HTTP requests that trick the server into processing administrative commands under the guise of a standard user session. The exploitation often involves intercepting network traffic using tools like Burp Suite or OWASP ZAP, modifying parameters related to vendor IDs, membership levels, or approval statuses, and resubmitting these payloads without valid authentication tokens for higher privileges. Because WordPress plugins frequently handle sensitive business logic involving financial transactions and customer data, this type of vulnerability poses a severe risk to the integrity of the entire platform.
The operational impact of this privilege escalation is profound, as it effectively grants attackers full administrative control over specific aspects of the multi-vendor marketplace without needing valid administrator credentials. An exploited instance can lead to unauthorized creation or modification of membership tiers, allowing malicious actors to grant themselves or other users elevated access levels that persist across sessions. Furthermore, attackers may manipulate vendor approval processes to onboard fraudulent vendors who sell counterfeit goods or engage in phishing activities, thereby damaging the reputation and trustworthiness of the marketplace owner. In more severe scenarios, this vulnerability can serve as a stepping stone for further attacks, including cross-site scripting if input sanitization is also lacking, or SQL injection if database queries are constructed unsafely based on manipulated inputs. The ability to alter subscription data directly impacts revenue streams and customer retention metrics, making the financial implications significant alongside the reputational damage.
This vulnerability aligns with CWE-269, which describes Improper Privilege Management, specifically highlighting cases where an actor is able to elevate privileges beyond what was originally intended by the system design. It also maps closely to MITRE ATT&CK technique T1078, Valid Accounts, particularly in contexts where attackers leverage existing low-level accounts to gain higher access levels within a network or application environment. The lack of robust server-side validation for role-based permissions is a common pattern in poorly audited WordPress plugins, underscoring the importance of rigorous code review and adherence to secure coding standards during development. Organizations utilizing this plugin must recognize that default configurations are not sufficient protection against such logical flaws, as they rely entirely on correct implementation rather than external security controls alone.
To mitigate this risk, immediate action is required by upgrading the WCMp Membership plugin to a version newer than 2.11.11 where these access control checks have been corrected and validated by developers. Administrators should ensure that their WordPress environment includes all available updates for core software and related plugins to maintain defense-in-depth strategies. Additionally, implementing Web Application Firewalls can provide an additional layer of protection by detecting anomalous request patterns associated with privilege escalation attempts, such as unusual POST requests from subscriber accounts targeting administrative endpoints. Regular security audits using static application security testing tools configured to detect CWE-269 violations are recommended for development teams to prevent similar logical flaws in future releases. Monitoring user activity logs for unexpected changes made by low-privileged users can also aid in early detection of exploitation attempts, allowing for rapid incident response before significant damage occurs.