CVE-2025-13666 is a vulnerability classified under CWE-862 (Missing Authorization) found in the Helloprint WordPress plugin that connects WooCommerce stores to Helloprint's customized print product catalog. The vulnerability exists because the plugin exposes a public REST API endpoint (/wp-json/helloprint/v1/complete_order_from_helloprint_callback) without enforcing authorization checks to verify the authenticity of incoming requests. This design flaw allows unauthenticated attackers to invoke this endpoint and arbitrarily modify the status of WooCommerce orders by providing a valid order reference ID. The vulnerability affects all versions up to and including 2.1.2 of the plugin. The CVSS v3.1 base score is 5.3 (medium severity), reflecting that the attack vector is network-based, requires no privileges or user interaction, and impacts integrity but not confidentiality or availability. The lack of authorization means that attackers can manipulate order statuses, potentially causing financial discrepancies, order fulfillment errors, or fraudulent order processing. No patches are currently available, and no known exploits have been reported in the wild. The vulnerability was publicly disclosed on December 6, 2025, with Wordfence as the assigner. Given the widespread use of WooCommerce in e-commerce and the plugin's role in order management, this vulnerability poses a tangible risk to affected online stores.

For European organizations, the impact of this vulnerability can be significant, particularly for e-commerce businesses relying on WooCommerce and Helloprint integration. Unauthorized modification of order statuses can lead to financial losses through fraudulent order completions or cancellations, disruption of order fulfillment processes, and damage to customer trust. Since the vulnerability does not affect confidentiality or availability, data breaches or service outages are less likely; however, integrity violations can undermine business operations and compliance with consumer protection regulations such as GDPR. The ability to exploit this vulnerability remotely without authentication increases the risk of automated or large-scale attacks. European companies with high transaction volumes or those in competitive markets may suffer reputational damage if customers experience order mishandling. Additionally, regulatory scrutiny could increase if order manipulation leads to consumer complaints or financial discrepancies.

To mitigate this vulnerability, affected organizations should immediately implement access controls to restrict the vulnerable REST API endpoint. This can be done by configuring web application firewalls (WAFs) or reverse proxies to block unauthorized requests to /wp-json/helloprint/v1/complete_order_from_helloprint_callback. Additionally, custom authorization logic should be added to the plugin or via WordPress hooks to verify the legitimacy of requests, ensuring only authenticated and authorized users or systems can modify order statuses. Monitoring and alerting on unusual order status changes can help detect exploitation attempts early. Organizations should also maintain regular backups of order data to enable recovery from unauthorized modifications. Until an official patch is released, consider disabling the Helloprint plugin if feasible or isolating it in a staging environment. Finally, keep abreast of vendor updates and apply patches promptly once available.