CVE-2025-64209 identifies a Missing Authorization vulnerability in the StylemixThemes Masterstudy WordPress plugin, affecting all versions prior to 4.8.122. The core issue is that certain functionalities within the plugin are not properly constrained by Access Control Lists (ACLs), allowing unauthorized users to invoke functions that should be restricted. This can lead to unauthorized access to administrative or sensitive features, potentially enabling attackers to manipulate course content, user data, or site configurations. The vulnerability does not require prior authentication, increasing its risk profile, and no user interaction is necessary to exploit it. Although there are no known exploits in the wild at the time of publication, the flaw presents a significant risk due to the widespread use of Masterstudy in e-learning environments. The absence of a CVSS score limits precise quantification, but the nature of the vulnerability suggests a high impact on confidentiality and integrity, with moderate impact on availability. The vulnerability was reserved in late October 2025 and published in December 2025, indicating recent discovery and disclosure. No official patches or mitigations have been linked yet, emphasizing the need for vigilance and proactive security measures by administrators.

For European organizations, particularly those operating e-learning platforms using the Masterstudy plugin, this vulnerability poses a serious risk. Unauthorized access to restricted functionality can lead to data breaches involving student records, course materials, and personal information, violating GDPR and other data protection regulations. Integrity of educational content and user roles may be compromised, allowing attackers to alter grades, course availability, or user permissions. This can disrupt educational services and damage institutional reputations. Additionally, attackers might leverage this access to pivot within the network or deploy further attacks. The impact is heightened in sectors with critical training needs such as healthcare, finance, and government, where compromised learning platforms could have broader operational consequences.

Organizations should immediately inventory their WordPress installations to identify the use of the Masterstudy plugin and its version. Until an official patch is released, restrict access to the WordPress admin area using IP whitelisting or VPNs to limit exposure. Implement strict role-based access controls and audit user permissions to ensure minimal privilege principles are enforced. Monitor logs for unusual access patterns or unauthorized function calls related to Masterstudy. Employ Web Application Firewalls (WAFs) with custom rules to block suspicious requests targeting plugin endpoints. Stay informed through vendor advisories and apply patches promptly once available. Additionally, consider isolating the e-learning environment from critical internal networks to reduce lateral movement risk.