CVE-2026-19535: Advantech EKI-1242IEIMS CSRF Vulnerability

CVE-2026-19535 Overview

CVE-2026-19535 is a Cross-Site Request Forgery [CWE-352] vulnerability in the LuCI administrative web interface of the Advantech EKI-1242IEIMS industrial protocol gateway running firmware version V1.06.01. Nozomi Networks Labs identified the flaw, which allows a remote unauthenticated attacker to trigger unauthorized state-changing requests on behalf of a logged-in administrator. Successful exploitation grants access to privileged management functions on the device. The issue affects industrial environments where the gateway bridges serial protocols to Ethernet networks.

Critical Impact
An attacker who convinces an authenticated administrator to visit a malicious page can execute privileged configuration changes on the industrial gateway without credentials.

Affected Products

Advantech EKI-1242IEIMS Industrial Protocol Gateway
Firmware version V1.06.01
LuCI administrative web interface component

Discovery Timeline

2026-09-16 - CVE-2026-19535 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-19535

Vulnerability Analysis

The LuCI administrative web interface exposed on the EKI-1242IEIMS does not enforce anti-CSRF protections on state-changing HTTP requests. Administrative endpoints accept requests based solely on the presence of a valid session cookie, without validating an origin-bound token or the Origin and Referer headers. An attacker hosts a malicious page or embeds a crafted request in a resource loaded by the administrator's browser. When the administrator is authenticated to LuCI, the browser automatically attaches the session cookie to the forged request. The gateway processes the request as legitimate and applies configuration changes with administrator privileges. Because industrial gateways often remain logged in for extended maintenance windows, the attack window is wide.

Root Cause

The root cause is the absence of Cross-Site Request Forgery countermeasures on privileged LuCI endpoints. State-changing operations lack per-session anti-CSRF tokens and do not verify request provenance headers. The interface treats any authenticated request as authorized regardless of origin.

Attack Vector

The vulnerability requires network reachability to the target device and user interaction from an authenticated administrator. The attacker delivers a malicious link or HTML resource through phishing, a compromised website, or a watering-hole page. When the administrator loads the resource with an active LuCI session, the browser issues the attacker-controlled request. No credentials, prior authentication, or elevated privileges are required from the attacker.

// No verified public exploit code is available for CVE-2026-19535.
// Refer to the Nozomi Networks and Advantech advisories linked below for technical details.

Detection Methods for CVE-2026-19535

Indicators of Compromise

Unexpected configuration changes to the EKI-1242IEIMS gateway, including new administrative accounts, altered network settings, or modified serial-to-Ethernet mappings.
LuCI access logs showing state-changing POST requests with Referer or Origin headers pointing to external domains.
Administrator browser history containing visits to unfamiliar sites immediately preceding gateway configuration changes.

Detection Strategies

Inspect HTTP traffic to the LuCI interface for cross-origin requests carrying valid session cookies to sensitive endpoints.
Correlate device configuration change events with administrator web browsing activity from workstations used for management.
Monitor for anomalous timing patterns, such as configuration writes occurring outside scheduled maintenance windows.

Monitoring Recommendations

Forward LuCI audit logs and gateway configuration events to a centralized SIEM for correlation with endpoint and network telemetry.
Alert on any administrative session activity originating from unusual source addresses or browser user-agents.
Baseline normal LuCI request patterns and flag deviations in request frequency, endpoint mix, or referer distribution.

How to Mitigate CVE-2026-19535

Immediate Actions Required

Restrict network access to the EKI-1242IEIMS LuCI interface to a dedicated management VLAN or jump host.
Instruct administrators to log out of the LuCI interface immediately after every configuration task and to avoid browsing other sites while authenticated.
Apply firmware updates from Advantech as soon as a fixed release is available and validated in the environment.

Patch Information

Refer to the Advantech Security Advisory EKI-1242IEIMS and the Nozomi Networks CVE-2026-19535 Advisory for the current patch status and remediation guidance from the vendor.

Workarounds

Use a dedicated browser profile or isolated management workstation solely for accessing the gateway to eliminate cross-site request paths.
Enforce short session timeouts and require re-authentication for privileged operations where the interface supports it.
Deploy a reverse proxy or web application firewall that validates Origin and Referer headers on requests to the LuCI interface.

bash

# Example: restrict LuCI access to a management subnet using iptables on an upstream firewall
iptables -A FORWARD -p tcp -d <gateway_ip> --dport 80 -s 10.10.50.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <gateway_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <gateway_ip> --dport 443 -s 10.10.50.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <gateway_ip> --dport 443 -j DROP