CVE-2025-13935 is a vulnerability identified in the Tutor LMS plugin for WordPress, a widely used eLearning and online course management solution. The flaw arises from missing authorization checks in the 'mark_course_complete' function, which fails to verify whether a user is properly enrolled in a course before allowing them to mark it as completed. This missing enrollment verification (classified under CWE-862: Missing Authorization) permits any authenticated user with subscriber-level privileges or higher to fraudulently mark courses as completed, bypassing normal course progression and completion requirements. The vulnerability affects all versions up to and including 3.9.2 of the plugin. The CVSS 3.1 base score is 4.3 (medium severity), reflecting that the attack vector is network-based and requires low privileges but does not impact confidentiality or availability, only integrity. No user interaction is needed beyond authentication, and no known exploits have been reported in the wild. The lack of patch links indicates that a fix has not yet been publicly released. This vulnerability undermines the integrity of course completion data, potentially allowing users to gain unauthorized certifications or progress without fulfilling course requirements, which can damage the trustworthiness of eLearning platforms relying on Tutor LMS.

For European organizations, especially educational institutions, corporate training departments, and certification bodies using Tutor LMS, this vulnerability can lead to significant integrity issues. Unauthorized course completion can result in fraudulent certifications, devaluing legitimate achievements and potentially causing reputational damage. In regulated sectors or where compliance training is mandatory, this could lead to non-compliance risks if users bypass required training. While confidentiality and availability remain unaffected, the integrity compromise could undermine trust in eLearning platforms and necessitate costly audits or revalidation of training records. The impact is particularly relevant for organizations relying heavily on automated course completion tracking for employee development or regulatory compliance.

Until an official patch is released, organizations should implement strict access controls to limit subscriber-level permissions and monitor user activities related to course completion. Administrators can audit course completion logs regularly to detect anomalous completions inconsistent with enrollment records. Consider disabling the 'mark_course_complete' functionality for lower-privileged users via custom code or plugin configuration if feasible. Employ web application firewalls (WAFs) to detect and block suspicious requests targeting the vulnerable function. Additionally, organizations should maintain up-to-date backups of LMS data to allow restoration if fraudulent completions are detected. Once a vendor patch is available, prioritize its deployment and verify that enrollment verification is properly enforced. Educate users and administrators about the risk and encourage reporting of suspicious course completions.