CVE-2025-4800 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) found in the MasterStudy LMS Pro plugin for WordPress, developed by StylemixThemes. The flaw exists in the stm_lms_add_assignment_attachment function, which fails to properly validate the type of files uploaded by users. This deficiency allows authenticated users with minimal privileges (Subscriber-level or higher) to upload arbitrary files to the server hosting the WordPress site. Because the plugin does not restrict or sanitize the file types, attackers can upload malicious scripts or executables, potentially enabling remote code execution (RCE). The vulnerability affects all versions up to and including 4.7.0, and no patches have been officially released at the time of this report. The CVSS v3.1 base score is 8.8, reflecting a network attack vector with low attack complexity, requiring privileges but no user interaction, and resulting in high confidentiality, integrity, and availability impacts. Although no known exploits are currently in the wild, the vulnerability poses a serious risk due to the common deployment of this LMS plugin in educational institutions and training platforms, which often contain sensitive user data and critical operational information.

The impact of CVE-2025-4800 is significant for organizations using the MasterStudy LMS Pro plugin. Successful exploitation can lead to remote code execution, allowing attackers to execute arbitrary commands on the web server. This can result in full system compromise, data theft, defacement, or use of the server as a pivot point for further attacks within the network. Educational institutions and e-learning platforms are particularly at risk, as they often store personal information, academic records, and payment data. The vulnerability undermines the confidentiality, integrity, and availability of affected systems. Additionally, since the attack requires only Subscriber-level access, which is commonly granted to registered users or students, the attack surface is broad. The absence of public exploits currently reduces immediate risk but does not diminish the urgency for remediation, as attackers could develop exploits rapidly once details are publicized.

To mitigate CVE-2025-4800, organizations should immediately upgrade the MasterStudy LMS Pro plugin to a patched version once available from StylemixThemes. Until a patch is released, administrators should restrict file upload permissions by limiting the roles allowed to upload files, ideally disabling uploads for Subscriber-level users. Implement server-side file type validation and filtering using web application firewalls (WAFs) or custom rules to block dangerous file extensions such as .php, .exe, .js, and others. Employ strict file upload directory permissions to prevent execution of uploaded files, for example, by disabling script execution in upload directories via web server configuration (e.g., using .htaccess rules in Apache). Monitor logs for unusual file upload activity and scan uploaded files for malware. Additionally, consider deploying intrusion detection/prevention systems (IDS/IPS) to detect exploitation attempts. Educate users about the risk and enforce strong authentication policies to reduce the likelihood of compromised accounts being used for exploitation.