CVE-2026-28270 is a vulnerability identified in the Kiteworks private data network (PDN) product, specifically affecting versions prior to 9.2.0. The root cause is an unrestricted file upload flaw categorized under CWE-434, where the system fails to properly validate file types during upload operations. This allows malicious administrators—users with elevated privileges—to upload arbitrary and potentially dangerous file types to the system. Since Kiteworks is used for secure data exchange and storage, the ability to upload unauthorized files can compromise the integrity of the system by introducing malicious scripts, executables, or other harmful content. The vulnerability requires administrative privileges (PR:H) but no user interaction (UI:N) and can be exploited remotely over the network (AV:N) with low attack complexity (AC:L). The CVSS v3.1 base score is 4.9, reflecting a medium severity level primarily due to the requirement for privileged access and the lack of direct confidentiality or availability impact. Kiteworks addressed this vulnerability in version 9.2.0 by implementing proper file type validation controls to prevent unauthorized uploads. No known exploits are currently reported in the wild, but the risk remains for organizations running outdated versions with insufficient administrative controls.

The primary impact of CVE-2026-28270 is on the integrity of the Kiteworks system. By allowing malicious administrators to upload arbitrary files, attackers can introduce unauthorized or malicious content that may alter system behavior, compromise data integrity, or facilitate further attacks such as privilege escalation or persistence mechanisms. Although confidentiality and availability are not directly affected, the integrity compromise can indirectly lead to data breaches or system misuse. Organizations relying on Kiteworks for secure data transfer and storage could face operational disruption or reputational damage if this vulnerability is exploited. The requirement for administrative privileges limits the attack surface to insiders or compromised admin accounts, but the risk remains significant in environments with weak access controls or insufficient monitoring.

To mitigate CVE-2026-28270, organizations should immediately upgrade Kiteworks installations to version 9.2.0 or later, where the vulnerability is patched with proper file type validation. Additionally, organizations must enforce strict administrative access controls, including multi-factor authentication and least privilege principles, to reduce the risk of malicious insiders exploiting this flaw. Regular audits of administrator activities and file uploads should be conducted to detect anomalous behavior. Implementing network segmentation and monitoring for unusual file upload patterns can further reduce risk. Where upgrading is not immediately possible, temporarily restricting file upload permissions or disabling upload features for administrators not requiring them can serve as a stopgap measure. Finally, organizations should maintain up-to-date incident response plans to quickly address any exploitation attempts.