CVE-2026-28270
Accellion Kiteworks ≤ 9.2.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:NSummary
CVE-2026-28270 is a medium-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability in Accellion Kiteworks. Its CVSS base score is 4.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 26% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-3 (Malicious Code Protection) and CM-7 (Least Functionality) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-28270 is an unrestricted upload of files with dangerous type vulnerability (CWE-434) affecting Kiteworks, a private data network (PDN), in versions prior to 9.2.0. The issue stems from inadequate validation in the Kiteworks configuration, enabling the upload of arbitrary files without proper checks on file types. It has a CVSS v3.1 base score of 4.9 (AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N), indicating medium severity primarily due to high integrity impact.
Malicious administrators with high privileges (PR:H) can exploit this vulnerability over the network with low complexity and no user interaction required. Successful exploitation allows attackers to upload unauthorized file types to the system, potentially compromising data integrity by introducing malicious or unintended content.
The Kiteworks security advisory at https://github.com/kiteworks/security-advisories/security/advisories/GHSA-v8x9-vwg6-cj45 details the patch in version 9.2.0, which addresses the configuration flaw and prevents arbitrary file uploads. Security practitioners should upgrade to Kiteworks 9.2.0 or later to mitigate the risk.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9065
Vulnerability Data
Kiteworks is a private data network (PDN). Prior to version 9.2.0, a vulnerability in Kiteworks configuration allows uploading of arbitrary files without proper validation. Malicious administrators could exploit this to upload unauthorized file types to the system. Version 9.2.0 contains…
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a patch for the issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.1.1
Mitigating Controls (NIST 800-53 r5) AI
Malicious-code protection at entry points blocks dangerous file types from being accepted and executed.
Least functionality restricts the file types and automatic processing capabilities the system will accept.
Mobile-code controls define, authorize, and block unacceptable uploaded code before automatic processing occurs.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Restricting execution of unauthorized software directly blocks dangerous uploaded files from running.
Hardened configuration baselines can enforce allowed file types and processing rules.
Secure development practices include input validation and file-type restrictions that prevent this weakness.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Configuration and acceptance testing verify that file-upload handling enforces allowed types and does not permit dangerous content to be stored or executed.
Secure-coding guidelines and security testing explicitly address restrictions on allowed file types and upload handling, reducing the risk that dangerous file uploads are accepted without validation.
Mandated testing for malicious content and known vulnerabilities reduces the likelihood that an outsourced component will contain or accept dangerous file types that could later be uploaded or executed.
Application allow-listing and pre-use scanning of received files directly blocks the introduction of executable content that has not been vetted, eliminating the primary vector for unrestricted dangerous file uploads.