CVE-2025-31100 is a critical vulnerability identified in the Mojoomla School Management software, versions up to 1.93.1 as of February 7, 2025. This vulnerability is classified under CWE-434: Unrestricted Upload of File with Dangerous Type. It allows an attacker with at least low privileges (PR:L) and no user interaction (UI:N) to upload arbitrary files, including web shells, to the web server hosting the application. The vulnerability is remotely exploitable over the network (AV:N) with low attack complexity (AC:L). The scope of the vulnerability is changed (S:C), meaning the exploit can affect resources beyond the initially vulnerable component. The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), indicating that an attacker can fully compromise the affected system. The lack of any patch links suggests that no official fix has been released at the time of this report. Although no known exploits are currently observed in the wild, the critical CVSS score of 9.9 underscores the urgency of addressing this vulnerability. The core technical issue is insufficient validation or filtering of uploaded files, allowing dangerous file types such as executable scripts or web shells to be placed on the server, which can lead to remote code execution, data theft, or system disruption.

For European organizations using Mojoomla School Management software, this vulnerability poses a severe risk. Successful exploitation could lead to full system compromise, allowing attackers to execute arbitrary code on the server, steal sensitive student and staff data, disrupt educational services, or use the compromised server as a pivot point for further attacks within the network. Given the critical nature of educational data and the increasing reliance on digital platforms in European schools, such an incident could result in significant operational disruption, regulatory penalties under GDPR for data breaches, and reputational damage. Additionally, the ability to upload web shells without user interaction or complex prerequisites increases the likelihood of automated exploitation attempts, especially in environments where the software is internet-facing. The impact extends beyond confidentiality to integrity and availability, potentially causing long-term damage to the affected institutions.

Immediate mitigation steps include implementing strict file upload validation and filtering at the application and web server levels. Organizations should restrict allowed file types to only those necessary for legitimate use, employing whitelist approaches rather than blacklists. Deploy web application firewalls (WAFs) with rules to detect and block web shell upload attempts and suspicious file extensions. Monitor upload directories for unexpected file types and unusual activity. Limit user privileges to the minimum necessary to reduce the risk of exploitation by low-privileged users. Isolate the application server from critical internal networks to contain potential breaches. Until an official patch is released, consider disabling file upload functionality if feasible or applying custom patches or third-party security modules that enforce upload restrictions. Regularly audit and review logs for signs of exploitation attempts. Finally, maintain up-to-date backups and have an incident response plan ready to quickly remediate any compromise.