CVE-2026-73171 Overview
CVE-2026-73171 is an External Control of File Name or Path vulnerability [CWE-73] in the backup-restore workflow of the Advantech EKI-1242EIMS industrial gateway running firmware V1.06.01. A remote authenticated attacker can upload a crafted backup archive through the web management interface and overwrite arbitrary files on the device filesystem. Nozomi Networks Labs discovered and reported the flaw. Advantech published a security advisory addressing the issue.
Critical Impact
Authenticated attackers can overwrite arbitrary files on the device, enabling configuration tampering, persistence, and potential full compromise of the industrial gateway.
Affected Products
- Advantech EKI-1242EIMS industrial protocol gateway
- Firmware version V1.06.01
- Web management interface backup-restore workflow
Discovery Timeline
- 2026-09-16 - CVE-2026-73171 published to the National Vulnerability Database
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-73171
Vulnerability Analysis
The Advantech EKI-1242EIMS exposes a backup-restore feature through its web management interface. Administrators use this feature to export and re-import device configuration archives. The restore handler processes uploaded archives without properly constraining file paths contained inside the archive. As a result, entries in a malicious archive can reference paths outside the intended restore directory. The device writes those entries directly to the resolved filesystem location during restore.
Because the affected component runs with high privileges on an embedded Linux-based gateway, arbitrary file overwrite escalates quickly. Attackers can replace configuration files, startup scripts, authentication data, or binaries used by the device runtime. This provides a path to persistence and, in many embedded designs, to code execution on the next service restart or reboot.
Root Cause
The root cause is external control of file name or path [CWE-73] during archive extraction. The restore routine trusts filename metadata supplied by the uploaded archive and does not enforce a canonical base directory. Attackers craft archive entries whose names include absolute paths or ../ traversal sequences to escape the extraction root.
Attack Vector
Exploitation requires network access to the web management interface and valid administrative credentials. The attacker crafts a backup archive containing entries with attacker-chosen destination paths, then submits the archive through the restore workflow. The device writes each entry to its supplied path, overwriting existing files. No user interaction is required beyond the attacker's own authenticated session.
Technical details are described in the Nozomi Networks CVE-2026-73171 Advisory and the Advantech Security Advisory EKI-1242IEIMS.
Detection Methods for CVE-2026-73171
Indicators of Compromise
- Unexpected uploads to the backup-restore endpoint of the EKI-1242EIMS web interface
- Configuration files, startup scripts, or system binaries with modification timestamps that do not match legitimate maintenance windows
- Administrative logins from unusual source IP addresses immediately preceding a restore action
- Device reboots or service restarts that follow a restore operation without a corresponding change record
Detection Strategies
- Inspect HTTP requests to the restore endpoint and flag archive uploads not originating from approved engineering workstations
- Compare deployed device configuration hashes against a known-good baseline to identify unauthorized overwrites
- Correlate authentication events with restore actions to identify sessions performing rapid restore operations after login
- Alert on any archive upload containing path traversal sequences or absolute paths in entry names when network inspection is available
Monitoring Recommendations
- Forward web management interface access logs and audit logs from the EKI-1242EIMS to a centralized log platform for retention and analysis
- Monitor OT network segments for unexpected HTTP or HTTPS sessions targeting management interfaces of Advantech gateways
- Track firmware version and configuration drift across the fleet to detect unauthorized changes
How to Mitigate CVE-2026-73171
Immediate Actions Required
- Apply the firmware update published by Advantech in the vendor advisory for EKI-1242EIMS
- Restrict network reachability of the web management interface to a dedicated management VLAN or jump host
- Rotate administrative credentials on affected devices and remove any unused accounts
- Audit recent restore actions and compare current device configuration against a trusted baseline
Patch Information
Advantech has released updated firmware addressing CVE-2026-73171. Refer to the Advantech Security Advisory EKI-1242IEIMS for the fixed firmware version and update procedure. Verify firmware image integrity before deployment and schedule updates within approved OT change windows.
Workarounds
- Disable or block access to the backup-restore endpoint when the vendor patch cannot be applied immediately
- Enforce strong, unique administrative credentials and multi-factor authentication on the jump host used to reach the device
- Place the gateway behind a firewall that permits management access only from named engineering hosts
- Monitor for and alert on any use of the restore workflow until patching is complete
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.