CVE-2025-3530 is a vulnerability identified in the WordPress Simple Shopping Cart plugin developed by mra13, affecting all versions up to and including 5.1.2. The core issue stems from a logic flaw related to inconsistent parameter usage during the process of adding products to the shopping cart. Specifically, the plugin uses two different parameters for price handling: 'product_tmp_two' is used internally to compute a security hash intended to prevent price tampering, while 'wspsc_product' is used to display product information to the user. This discrepancy allows an unauthenticated attacker to manipulate the 'wspsc_product' parameter by substituting it with details from a cheaper product, effectively bypassing payment for more expensive items. The vulnerability falls under CWE-472, which concerns external control of an assumed-immutable web parameter, indicating that the plugin incorrectly trusts client-supplied data that should be immutable or internally controlled. Exploitation does not require authentication or user interaction, making it accessible to any attacker who can interact with the affected WordPress site. Although no known exploits have been reported in the wild as of the publication date, the vulnerability presents a significant risk to e-commerce operations relying on this plugin. The lack of a patch at the time of disclosure further exacerbates the risk. The vulnerability primarily impacts the confidentiality and integrity of transaction data, allowing unauthorized price manipulation and potential financial loss. Availability is less directly affected but could be impacted indirectly if exploitation leads to disputes or service disruptions.

For European organizations using the WordPress Simple Shopping Cart plugin, this vulnerability poses a direct financial risk due to the potential for fraudulent transactions and revenue loss. E-commerce businesses, particularly small to medium-sized enterprises relying on this plugin for online sales, are most at risk. The integrity of pricing data is compromised, undermining customer trust and potentially leading to chargebacks or legal issues. Additionally, the exploitation of this vulnerability could damage brand reputation and customer confidence in affected businesses. Since the vulnerability allows unauthenticated attackers to manipulate prices, it could be exploited at scale, leading to significant cumulative losses. The impact extends beyond individual businesses to the broader European e-commerce ecosystem, especially in sectors where price integrity is critical, such as retail, digital goods, and services. Furthermore, organizations may face compliance challenges under European data protection and consumer protection regulations if they fail to secure their transaction processes adequately.

Given the absence of an official patch at the time of disclosure, European organizations should implement immediate compensating controls. These include: 1) Disabling or temporarily removing the WordPress Simple Shopping Cart plugin until a secure version is released. 2) Implementing server-side validation of all price-related parameters to ensure that client-supplied data cannot override internal pricing logic. 3) Employing web application firewalls (WAFs) with custom rules to detect and block requests attempting to manipulate 'wspsc_product' or related parameters. 4) Monitoring transaction logs for anomalies such as unusually low prices or mismatches between displayed and processed product data. 5) Educating development and operations teams about the vulnerability to ensure rapid response once patches become available. 6) Considering alternative, more secure e-commerce plugins with robust input validation and security track records. 7) Applying strict access controls and regularly auditing plugin configurations to minimize exposure. These measures go beyond generic advice by focusing on immediate risk reduction through parameter validation, monitoring, and temporary plugin deactivation.