CVE-2025-53900 identifies a privilege escalation vulnerability in Kiteworks Managed File Transfer (MFT) software versions before 9.1.0. The root cause is an unsafe definition of roles and permissions, specifically in how the system manages Connections within the application. Connections in Kiteworks MFT represent configurations for file transfer endpoints or protocols. Improperly defined roles allow authorized users with limited privileges to perform actions beyond their intended scope, leading to unexpected privilege escalation. This vulnerability is classified under CWE-267, which concerns privileges defined with unsafe actions. The CVSS v3.1 base score is 6.5 (medium), with an attack vector of network (AV:N), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), high integrity impact (I:H), and no availability impact (A:N). Exploiting this flaw could allow an attacker with legitimate access to elevate their permissions and potentially alter connection settings, which could undermine the integrity of file transfer workflows. The vulnerability was publicly disclosed on November 29, 2025, and has been patched in version 9.1.0 of Kiteworks MFT. No known exploits have been reported in the wild, but the risk remains for organizations running vulnerable versions. The issue highlights the importance of secure role and permission management in complex enterprise software handling sensitive data transfers.

For European organizations, this vulnerability poses a significant risk to the integrity of file transfer workflows managed by Kiteworks MFT. Unauthorized privilege escalation could allow malicious insiders or compromised accounts to alter connection configurations, potentially redirecting or intercepting sensitive data transfers without detection. Although confidentiality and availability are not directly impacted, the integrity breach could lead to data tampering or unauthorized data exposure indirectly. Industries such as finance, healthcare, legal, and government entities that rely on secure and compliant file transfers are particularly vulnerable. The disruption or manipulation of file transfer connections could also lead to compliance violations under GDPR and other data protection regulations, resulting in legal and reputational damage. Since exploitation requires existing privileges, the threat is more relevant to organizations with multiple users managing connections or with complex role assignments. The absence of known exploits reduces immediate risk but does not eliminate the need for urgent remediation given the potential impact.

European organizations using Kiteworks MFT should immediately verify their software version and upgrade to version 9.1.0 or later, where the vulnerability is patched. Review and audit role definitions and permissions related to managing Connections to ensure the principle of least privilege is enforced. Implement strict access controls and monitoring on privileged accounts that manage file transfer connections. Employ logging and alerting mechanisms to detect unusual changes to connection configurations. Conduct regular security training for administrators and users with elevated privileges to prevent misuse. If upgrading is not immediately feasible, consider restricting network access to the management interfaces of Kiteworks MFT to trusted IPs only. Additionally, perform periodic security assessments and penetration testing focused on privilege escalation vectors within the file transfer environment. Maintain an incident response plan that includes scenarios involving unauthorized privilege escalation and configuration tampering.