CVE-2025-31100 is a critical vulnerability identified in the Mojoomla School Management software, affecting versions up to 1.93.1 as of early 2025. The vulnerability is classified under CWE-434, which pertains to the unrestricted upload of files with dangerous types. This flaw allows an attacker with at least limited privileges (PR:L) to upload malicious files, such as web shells, directly to the web server hosting the application. The vulnerability does not require user interaction (UI:N) and can be exploited remotely over the network (AV:N). The vulnerability's scope is classified as changed (S:C), indicating that exploitation can affect resources beyond the initially vulnerable component, potentially compromising the entire system. The CVSS v3.1 base score is 9.9, reflecting a critical severity level due to the high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). By uploading a web shell, an attacker can execute arbitrary code on the server, leading to full system compromise, data theft, defacement, or pivoting to other internal systems. The vulnerability arises from insufficient validation or filtering of uploaded files, allowing dangerous file types to bypass security controls. No patches or mitigations were listed at the time of publication, and no known exploits in the wild have been reported yet. However, given the severity and ease of exploitation, this vulnerability poses a significant risk to organizations using the affected software.

For European organizations, the impact of this vulnerability could be severe, especially for educational institutions and administrative bodies relying on Mojoomla School Management software. Successful exploitation could lead to unauthorized access to sensitive student and staff data, including personal identifiable information (PII), academic records, and financial information. The compromise of the web server could also disrupt school operations, leading to downtime and loss of trust. Additionally, attackers could use the foothold to move laterally within the network, potentially impacting other connected systems. Given the criticality of educational data and the increasing regulatory scrutiny under GDPR, a breach could result in significant legal and financial penalties. The availability of the service could be severely impacted, affecting remote learning and administrative functions. Furthermore, the ability to upload web shells without user interaction increases the risk of automated attacks and rapid exploitation across multiple institutions.

To mitigate this vulnerability, European organizations should immediately implement strict file upload controls within the Mojoomla School Management environment. This includes enforcing whitelisting of allowed file types, validating file content beyond extensions, and scanning uploads with antivirus and malware detection tools. Implementing web application firewalls (WAF) with rules to detect and block web shell signatures can provide an additional layer of defense. Restricting upload permissions to only trusted users and monitoring upload directories for suspicious files is critical. Network segmentation should be employed to limit the impact of a compromised server. Organizations should also ensure that their systems are regularly backed up and that backups are stored securely offline. Since no official patch is currently available, organizations should engage with the vendor for updates and consider temporary compensating controls such as disabling file upload features if feasible. Continuous monitoring and incident response readiness are essential to detect and respond to any exploitation attempts promptly.