CVE-2021-4379 in WooCommerce Multi Currency Plugin
Summary
by MITRE • 06/07/2023
The WooCommerce Multi Currency plugin for WordPress is vulnerable to authorization bypass due to a missing capability check on the wmc_bulk_fixed_price function in versions up to, and including, 2.1.17. This makes it possible for authenticated attackers, with subscriber-level permissions and above, to make changes to product prices.
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Analysis
by VulDB Data Team • 04/09/2026
The WooCommerce Multi Currency plugin vulnerability represents a critical authorization bypass flaw that undermines the security model of WordPress e-commerce systems. This issue affects versions up to and including 2.1.17 of the plugin, which is widely used across WordPress installations for managing multi-currency transactions. The vulnerability stems from a fundamental missing capability check within the wmc_bulk_fixed_price function, creating a pathway for unauthorized modifications to product pricing structures. The flaw specifically targets authenticated users who possess subscriber-level permissions or higher, which is particularly concerning given that subscribers typically should not have administrative capabilities within e-commerce platforms.
The technical implementation of this vulnerability lies in the absence of proper access control validation within the plugin's core functionality. When the wmc_bulk_fixed_price function processes bulk price modifications, it fails to verify whether the requesting user possesses the appropriate administrative privileges required for such operations. This missing capability check creates a direct exploitation vector where attackers can manipulate product pricing without proper authorization. The vulnerability operates at the application layer and can be exploited through the plugin's administrative interface, making it accessible to users who should not have the ability to modify core commerce data. This flaw aligns with CWE-284, which specifically addresses improper access control issues in software systems.
The operational impact of this vulnerability extends beyond simple price manipulation, potentially enabling significant financial fraud and market disruption. Attackers with subscriber-level access can alter product pricing across multiple items simultaneously, creating opportunities for revenue loss, competitive advantage manipulation, or market disruption. The bulk nature of the affected function means that a single exploitation can affect numerous products at once, amplifying the potential damage. This vulnerability particularly impacts businesses relying on WooCommerce for their online commerce operations, where unauthorized price modifications could lead to substantial financial losses and customer trust erosion. The risk is compounded by the fact that many WordPress installations do not maintain strict user permission controls, leaving subscriber accounts potentially exposed to such attacks.
Mitigation strategies for this vulnerability should focus on immediate remediation through plugin updates to versions that include the proper capability checks. System administrators must ensure that all WooCommerce Multi Currency installations are updated to the latest secure version, which addresses the authorization bypass issue. Additionally, implementing strict user role management practices is essential, including limiting the number of users with subscriber-level permissions and ensuring that only authorized personnel have access to administrative functions. Network monitoring solutions should be configured to detect unusual bulk price modification activities, as these operations may indicate exploitation attempts. Organizations should also consider implementing the principle of least privilege, ensuring that users have only the minimum permissions necessary for their specific roles. This vulnerability demonstrates the critical importance of proper access control implementation in e-commerce platforms and aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation through unauthorized access to system functions.