The Fluent Forms plugin for WordPress, widely used for creating customizable contact forms, surveys, quizzes, and conversational forms, contains an authorization bypass vulnerability identified as CVE-2025-13748. This vulnerability arises from an insecure direct object reference (IDOR) flaw, classified under CWE-639, due to missing validation on the 'submission_id' parameter within the confirmScaPayment() function. Specifically, the plugin fails to verify that the user making the request is authorized to modify the status of a particular form submission. As a result, an unauthenticated attacker can craft HTTP requests with arbitrary 'submission_id' values to mark submissions as failed. The attack surface is limited to the ability to guess or enumerate valid submission identifiers, which may be sequential or predictable. The vulnerability affects all versions of the plugin up to and including 6.1.7. The CVSS v3.1 base score is 5.3, reflecting a medium severity level, with the vector indicating network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to integrity. There is no impact on confidentiality or availability. No patches or exploit code are currently publicly available, and no active exploitation has been reported. However, the vulnerability could be leveraged to disrupt form submission workflows, potentially impacting business processes relying on form data integrity.

The primary impact of this vulnerability is on the integrity of form submission data within affected WordPress sites using the Fluent Forms plugin. Attackers can manipulate submission statuses, marking legitimate submissions as failed, which could disrupt workflows such as customer inquiries, order forms, surveys, or quizzes. This may lead to loss of trust, operational inefficiencies, or erroneous business decisions based on altered data. Although confidentiality and availability are not directly affected, the ability to tamper with submission records without authentication poses a risk to data reliability and audit trails. Organizations relying heavily on these forms for critical communications or transactions may experience reputational damage or customer dissatisfaction. Additionally, attackers could use this flaw as part of a broader attack chain, for example, to cause confusion or denial of service at the application logic level. The ease of exploitation and lack of required privileges increase the risk, especially for sites with predictable submission IDs and no additional access controls.

To mitigate this vulnerability, organizations should immediately update the Fluent Forms plugin to a patched version once released by the vendor. In the absence of an official patch, administrators can implement temporary workarounds such as restricting access to the confirmScaPayment() endpoint via web application firewall (WAF) rules or IP whitelisting to trusted sources. Implementing rate limiting and monitoring for unusual patterns of submission_id requests can help detect enumeration attempts. Developers should enforce strict server-side authorization checks to validate that the requester is permitted to modify the specified submission. Additionally, obfuscating or randomizing submission identifiers can reduce the risk of enumeration. Regularly auditing plugin versions and applying security updates promptly is critical. Organizations should also review logs for suspicious activity related to submission status changes and educate site administrators about this vulnerability to ensure timely response.