CVE-2026-73174: Advantech EKI-1242EIMS Information Disclosure

CVE-2026-73174 Overview

CVE-2026-73174 is a cleartext transmission vulnerability [CWE-319] in the edgserver management protocol of the Advantech EKI-1242EIMS industrial protocol gateway. The affected firmware version V1.06.01 transmits management traffic without encryption. A network-adjacent passive observer can intercept this traffic and recover sensitive device identity and network metadata in cleartext. Nozomi Networks Labs identified and reported the flaw. The vulnerability carries a CVSS 4.0 score of 8.7 (HIGH) and requires only adjacent network access with no authentication or user interaction to exploit.

Critical Impact
Passive interception of unencrypted management traffic exposes device identity and network metadata, enabling reconnaissance for follow-on attacks against industrial control system (ICS) environments.

Affected Products

Advantech EKI-1242EIMS industrial protocol gateway
Firmware version V1.06.01
Deployments using the edgserver management protocol

Discovery Timeline

2026-09-16 - CVE-2026-73174 published to the National Vulnerability Database (NVD)
2026-09-16 - Last updated in NVD database
Vulnerability identified and reported by Nozomi Networks Labs

Technical Details for CVE-2026-73174

Vulnerability Analysis

The Advantech EKI-1242EIMS is an industrial protocol gateway used to bridge serial and Ethernet-based industrial protocols. Its edgserver component handles device management operations over the network. In firmware version V1.06.01, this management channel transmits data without encryption or integrity protection.

An attacker with access to the same Layer 2 broadcast domain, such as a compromised host or a rogue device on the OT segment, can passively capture management traffic. The exposed data includes device identity information and network metadata that supports reconnaissance and targeted follow-on attacks. Because the observation is passive, exploitation leaves no trace on the gateway itself.

This class of weakness maps to [CWE-319: Cleartext Transmission of Sensitive Information]. Industrial gateways are frequently deployed at the boundary between IT and OT networks, so information disclosed through cleartext protocols can accelerate lateral movement into control systems.

Root Cause

The root cause is the absence of transport-layer encryption in the edgserver management protocol implementation. The protocol was designed to carry management payloads in plaintext rather than tunneling them over TLS or a comparable encrypted channel. Without cryptographic protections, any device sharing the local network segment can observe protocol contents in full.

Attack Vector

Exploitation requires adjacent network access (AV:A) and no privileges or user interaction. An attacker positions a monitoring host on the same network segment as the EKI-1242EIMS gateway and captures traffic using standard packet capture tools. The attacker then parses the edgserver frames to extract device identity and network metadata for use in later stages of an intrusion. See the Nozomi Networks CVE-2026-73174 Advisory for protocol-level details.

Detection Methods for CVE-2026-73174

Indicators of Compromise

Unexpected edgserver management traffic observed on OT network segments outside of scheduled maintenance windows.
Presence of unauthorized hosts on VLANs containing Advantech EKI-1242EIMS gateways.
Packet captures containing cleartext EKI management payloads originating from or destined to non-administrative endpoints.

Detection Strategies

Deploy passive network monitoring on OT segments to inventory devices communicating with the EKI-1242EIMS and flag new or unauthorized peers.
Use deep packet inspection to identify edgserver protocol frames traversing the network and correlate against an approved management source list.
Alert on ARP anomalies, port mirroring changes, or promiscuous-mode interfaces that indicate a passive sniffer on shared segments.

Monitoring Recommendations

Continuously baseline management-plane traffic to the gateway and detect deviations in volume, direction, or client identity.
Forward switch and firewall logs to a centralized data lake for correlation with asset inventory and access records.
Review physical and virtual switch port assignments regularly to confirm no unauthorized taps or mirror sessions exist.

How to Mitigate CVE-2026-73174

Immediate Actions Required

Isolate Advantech EKI-1242EIMS devices onto dedicated management VLANs with strict access control lists (ACLs) limiting which hosts can reach the edgserver service.
Restrict administrative access to trusted engineering workstations and disable management access from general-purpose or user networks.
Inventory all EKI-1242EIMS units running firmware V1.06.01 and prioritize them for the vendor-supplied update.

Patch Information

Refer to the Advantech Security Advisory EKI-1242IEIMS for the vendor's remediation guidance and updated firmware availability. Apply the update following standard OT change-management procedures and validate device functionality after upgrade.

Workarounds

Tunnel management sessions through an encrypted channel such as an IPsec or VPN overlay when native encryption is unavailable.
Enforce port security and 802.1X on switches serving the OT segment to prevent unauthorized devices from joining the broadcast domain.
Disable the edgserver management protocol when not actively required and use out-of-band console access for device configuration.

bash

# Example: restrict management access to the EKI-1242EIMS via an ACL
access-list 150 permit ip host 10.10.20.5 host 10.10.30.10
access-list 150 deny   ip any host 10.10.30.10 log
access-list 150 permit ip any any
interface Vlan30
 description OT-Gateway-Management
 ip access-group 150 in