CVE-2026-73171 in EKI-1242EIMS
Summary
by MITRE • 09/16/2026
Nozomi Networks Labs identified a CWE-73: External Control of File Name or Path vulnerability in the backup-restore workflow of Advantech EKI-1242EIMS in firmware version V1.06.01 that allows a remote authenticated attacker to overwrite arbitrary files on the device filesystem by uploading a crafted backup archive through the web management interface.
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified as CWE-73, External Control of File Name or Path, represents a critical security flaw within the firmware version V1.06.01 of the Advantech EKI-1242EIMS industrial Ethernet switch. This specific weakness is located in the backup and restore workflow accessible via the device's web management interface. The core technical issue stems from insufficient validation or sanitization of user-supplied input when processing uploaded archive files intended for system restoration. Specifically, the application fails to adequately restrict file paths contained within the tarball or zip archive against directory traversal sequences such as dot-dot-slash characters. This lack of rigorous path normalization allows an attacker to manipulate the extraction destination by including maliciously crafted filenames that reference directories outside the designated backup restore scope.
From a technical perspective, this flaw enables a remote authenticated attacker to achieve arbitrary file write operations on the device's underlying operating system filesystem. By uploading a specially constructed archive containing files with paths like etc/passwd or other critical configuration and binary locations, the attacker can overwrite essential system files. This capability bypasses standard access controls because the vulnerability exploits the administrative privileges inherent in the backup-restore function itself. The attack vector is classified as remote but requires authentication, meaning the adversary must first compromise valid credentials for the web management interface before they can exploit this path traversal mechanism to write malicious content to sensitive areas of the file system.
The operational impact of this vulnerability is severe and potentially catastrophic for industrial control systems relying on this hardware. Overwriting critical files can lead to complete device compromise, allowing an attacker to install persistent backdoors, modify network configurations to facilitate lateral movement within a plant network, or disrupt operations by corrupting firmware images leading to denial of service. In the context of OT environments where availability and integrity are paramount, such a flaw undermines trust in the management plane. An adversary could potentially escalate privileges further if overwritten files include setuid binaries or configuration scripts that execute with higher system rights during boot processes. This aligns with ATT&CK techniques related to persistence mechanisms like T1505 (Server Software Component) and defense evasion through file manipulation, posing a significant risk to the integrity of industrial automation networks.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary solution is for Advantech to release a firmware update that patches this vulnerability by implementing strict input validation and canonicalization checks during archive extraction. Administrators should ensure their devices are updated to the latest patched version as soon as it becomes available. In the interim, if updating is not immediately feasible, organizations should restrict access to the web management interface using network segmentation policies, ensuring only authorized IP addresses can reach the device's administrative ports. Additionally, monitoring for unusual file system changes or unexpected process executions on managed devices can help detect exploitation attempts early. Regular audits of backup archives and enforcing least-privilege principles for user accounts accessing the management interface are also recommended to reduce the attack surface associated with this CWE-73 flaw.