CVE-2026-102089 in Email Protection Gateway
Summary
by MITRE • 10/01/2026
Kiteworks Email Protection Gateway before version 9.5.0 is vulnerable to a path traversal weakness in an administrative import function allowed an authenticated administrator to write files to arbitrary locations on the server. This could potentially be leveraged to execute arbitrary code on the underlying system.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified in Kiteworks Email Protection Gateway prior to version 9.5.0 represents a critical security flaw rooted in improper input validation within an administrative import function. Specifically, this is classified as CWE-22 Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal or directory traversal. The core technical issue arises from the application's failure to adequately sanitize user-supplied file paths during the upload process. When an authenticated administrator initiates an import operation, the system processes the provided filename and destination parameters without sufficiently verifying that the resulting file path remains within the intended secure directories. This lack of strict boundary enforcement allows a malicious actor to manipulate the input string using standard traversal sequences, such as dot-dot-slash characters, to break out of the designated upload sandbox.
The operational impact of this vulnerability is severe due to the privilege level required for exploitation and the nature of the resulting access. Because the flaw requires authentication, it targets users with administrative privileges within the Kiteworks environment. However, once an attacker gains control over these credentials or exploits a separate weakness to obtain them, they can leverage this path traversal issue to write files to arbitrary locations on the underlying operating system. This capability effectively bypasses standard application-level access controls and grants the attacker direct file system manipulation capabilities at the server level. The ability to place files in unrestricted directories significantly expands the attack surface beyond the web application itself into the host infrastructure.
The most critical consequence of this weakness is the potential for arbitrary code execution on the underlying system. By writing malicious scripts, shell codes, or executable binaries to locations where they can be executed by the server's process user or through subsequent service restarts, an attacker can achieve remote code execution. This transforms a simple file upload flaw into a full compromise of the host machine. The attacker could install backdoors, exfiltrate sensitive data stored on the gateway, pivot to other systems within the network, or disrupt services by corrupting critical system files. Given that email protection gateways often handle highly confidential communications and act as security perimeters, such a breach undermines the integrity and confidentiality guarantees provided by the entire platform.
To mitigate this risk, organizations running Kiteworks Email Protection Gateway must immediately upgrade to version 9.5.0 or later, where these input validation mechanisms have been corrected. In addition to patching, administrators should enforce strict least-privilege principles for administrative accounts, ensuring that only essential personnel possess elevated access rights and that multi-factor authentication is enabled to reduce the likelihood of credential compromise. Network segmentation strategies can also help limit lateral movement if a host is compromised, while continuous monitoring of file system changes in critical directories provides an additional layer of defense against unauthorized writes. Regular security audits and penetration testing focused on input validation flaws are recommended to identify similar weaknesses across other administrative functions within the application ecosystem.