CVE-2026-102137 in Kiteworks
Summary
by MITRE • 10/01/2026
An authenticated administrator could bypass the content validation applied to an administrative file upload and store a file containing dangerous content on the appliance. This did not by itself result in code execution, which would require a separate vulnerability to run the stored file.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/01/2026
The identified vulnerability represents a critical failure in input validation mechanisms within the application's administrative interface, specifically concerning file upload operations. An authenticated administrator possesses sufficient privileges to interact with these endpoints, yet the system fails to adequately sanitize or validate the content of uploaded files before storage. This flaw allows for the injection of malicious payloads disguised as legitimate data types. While the immediate action is limited to storing a dangerous file on the appliance's filesystem, this constitutes a significant security risk because it establishes a foothold that can be leveraged in conjunction with other vulnerabilities. The absence of strict content validation means that files containing executable scripts, web shells, or other harmful code segments are accepted and persisted without triggering appropriate rejection protocols or sanitization routines.
From a technical perspective, the core issue lies in the insufficient verification of file contents against expected formats or signatures. Many applications rely solely on filename extensions or MIME types for validation, which can be easily spoofed by an attacker. In this scenario, the application likely accepts files based on superficial attributes rather than performing deep packet inspection or content analysis to ensure the data matches the declared type. This oversight creates a pathway where an adversary with administrative access can place arbitrary code onto the server. Although the vulnerability description notes that code execution does not occur directly through this flaw alone, it serves as a critical enabler for subsequent exploitation steps. The stored file acts as persistent malware or a backdoor component waiting to be triggered by another system weakness, such as an insecure direct object reference or a path traversal issue that allows remote access and execution of the uploaded content.
The operational impact of this vulnerability is substantial due to its potential role in multi-stage attack chains. While a single authenticated administrator bypassing validation might seem like a low-impact internal policy violation, it fundamentally undermines the integrity of the application's storage layer. If an attacker can combine this file upload flaw with another vulnerability that allows for remote code execution or local privilege escalation, they gain full control over the affected appliance. This scenario aligns closely with CWE-434, which describes the unrestricted uploading of files with dangerous content. Furthermore, it relates to CWE-20, improper input validation, where the system fails to verify that user-supplied data conforms to expected constraints before processing. The ability to store malicious artifacts on a server is often a precursor to more severe compromises, including data exfiltration, lateral movement within a network, or complete service disruption through resource exhaustion via large file uploads.
Mitigation strategies must focus on implementing robust content validation and secure storage practices. Developers should enforce strict allow-lists for both file extensions and MIME types, ensuring that only expected document formats are accepted. Additionally, performing deep inspection of the file header bytes to verify actual content type is essential, as this prevents simple extension spoofing attacks. Files should be stored in a directory with execute permissions disabled to prevent immediate execution if accessed directly via web server misconfigurations. Renaming uploaded files upon storage can also help mitigate risks associated with predictable filenames or path traversal attempts. Implementing these controls ensures that even if an attacker bypasses initial checks, the system prevents the successful deployment of executable payloads. Regular security audits and static code analysis focused on file handling routines are recommended to identify similar weaknesses across other parts of the application architecture.