CVE-2025-48372 identifies a vulnerability in the open-source school management system software 'Schule' prior to version 1.0.1. The core issue lies in the generateOTP() function, which produces a 4-digit numeric One-Time Password (OTP). Despite the use of a secure random number generator, the OTP's short length and limited numeric range (1000 to 9999) restrict the keyspace to only 9000 possible combinations. This limited keyspace significantly weakens the OTP's security, making it susceptible to brute-force attacks. The vulnerability is exacerbated if the system lacks robust rate-limiting or account lockout mechanisms, allowing attackers to attempt multiple guesses without restriction. The CVSS 4.0 score of 6.6 (medium severity) reflects the vulnerability's network attack vector, low attack complexity, and no requirement for privileges or user interaction, but with a high impact on integrity due to potential unauthorized access. Version 1.0.1 of Schule addresses this issue by presumably increasing OTP complexity or implementing additional security controls. No known exploits are currently reported in the wild, but the vulnerability presents a tangible risk, especially in environments where OTPs are used for authentication or sensitive operations.

For European organizations, particularly educational institutions using the Schule management system, this vulnerability could lead to unauthorized access to sensitive student and staff data, manipulation of academic records, or disruption of school administrative functions. The brute-force susceptibility of the OTP mechanism could allow attackers to bypass authentication controls, potentially leading to data breaches or unauthorized system control. Given the critical nature of educational data and the increasing regulatory scrutiny under GDPR, such breaches could result in significant legal and reputational consequences. Moreover, compromised school systems could be leveraged as entry points for broader network attacks within educational or municipal infrastructures. The impact is heightened in institutions lacking comprehensive monitoring or incident response capabilities.

Organizations should immediately upgrade Schule to version 1.0.1 or later to benefit from the patched OTP generation mechanism. In addition to applying the patch, schools should implement strict rate-limiting and account lockout policies to prevent brute-force attempts on OTP inputs. Multi-factor authentication (MFA) should be enforced where possible, combining OTPs with other authentication factors to reduce reliance on numeric OTPs alone. Monitoring and alerting for repeated failed OTP attempts should be established to detect potential brute-force activities early. Where feasible, increasing OTP length and complexity beyond 4 digits, or adopting time-based OTPs (TOTP) compliant with established standards (e.g., RFC 6238), would further enhance security. Regular security audits and penetration testing focused on authentication mechanisms are recommended to identify and remediate similar weaknesses proactively.