CVE-2025-53899 is a vulnerability classified under CWE-941 (Incorrectly Specified Destination in a Communication Channel) affecting Kiteworks Managed File Transfer (MFT) products prior to version 9.1.0. The flaw arises from improper specification of communication channel destinations within the back-end architecture of Kiteworks MFT. An attacker who already possesses administrative privileges on the affected system can exploit this vulnerability to intercept upstream communications. This interception can lead to an escalation of privileges, allowing the attacker to gain higher-level access or control than initially permitted. The vulnerability impacts the confidentiality, integrity, and availability of data handled by the system, as intercepted communications may contain sensitive information or control commands. The CVSS v3.1 score of 7.2 reflects a high severity due to network attack vector (AV:N), low attack complexity (AC:L), required privileges being high (PR:H), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). The vulnerability was publicly disclosed on November 29, 2025, and has been addressed in Kiteworks MFT version 9.1.0. No known exploits have been observed in the wild, but the potential impact warrants immediate attention. Kiteworks MFT is widely used in enterprise environments for secure file transfer workflows, making this vulnerability particularly concerning for organizations handling sensitive or regulated data.

For European organizations, the impact of CVE-2025-53899 can be significant, especially for those relying on Kiteworks MFT for secure file transfers involving sensitive personal data, intellectual property, or regulated information such as financial or healthcare records. Successful exploitation could lead to unauthorized interception of data, resulting in data breaches, loss of confidentiality, and potential regulatory non-compliance under GDPR. The escalation of privileges could allow attackers to manipulate or disrupt file transfer workflows, impacting business continuity and data integrity. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and the reliance on secure file transfer solutions. The requirement for administrative privileges to exploit the vulnerability somewhat limits the attack surface but does not eliminate risk, as insider threats or compromised administrative accounts could be leveraged. The absence of known exploits in the wild suggests a window of opportunity for proactive mitigation before widespread exploitation occurs.

European organizations should immediately verify their Kiteworks MFT version and upgrade to version 9.1.0 or later, where the vulnerability is patched. Restrict and monitor administrative access rigorously to reduce the risk of privilege abuse. Implement strong authentication mechanisms such as multi-factor authentication (MFA) for administrative accounts. Conduct regular audits of system logs and communication channels to detect any anomalous interception or privilege escalation attempts. Employ network segmentation to isolate Kiteworks MFT servers and limit exposure to untrusted networks. Use encryption for all communication channels to reduce the risk of interception even if the destination is incorrectly specified. Establish an incident response plan specifically addressing potential misuse of administrative privileges and communication interception. Finally, maintain up-to-date threat intelligence feeds to monitor for any emerging exploits targeting this vulnerability.