CVE-2026-29521: Hereta ETH-IMC408M CSRF Vulnerability

CVE-2026-29521 Overview

CVE-2026-29521 is a Cross-Site Request Forgery (CSRF) vulnerability affecting Hereta ETH-IMC408M industrial motion controller firmware version 1.0.15 and prior. The vulnerability exists due to missing CSRF protections in the device's setup.cgi configuration endpoint. Attackers can exploit this flaw by hosting malicious web pages that submit forged requests to the device, leveraging automatically-included HTTP Basic Authentication credentials to modify device configuration without user consent.

Critical Impact

Successful exploitation allows unauthorized modification of device configuration including adding RADIUS accounts, altering network settings, or triggering diagnostic functions on affected industrial motion controllers.

Affected Products

• Hereta ETH-IMC408M firmware version 1.0.15 and prior

Discovery Timeline

• 2026-03-16 - CVE-2026-29521 published to NVD
• 2026-03-17 - Last updated in NVD database

Technical Details for CVE-2026-29521

Vulnerability Analysis

This vulnerability is classified under CWE-352 (Cross-Site Request Forgery). The Hereta ETH-IMC408M industrial motion controller lacks proper anti-CSRF token validation in its web-based configuration interface. When an authenticated administrator visits a malicious website while logged into the device's management interface, the attacker's page can submit forged HTTP requests to setup.cgi on the controller.

Since the device relies on HTTP Basic Authentication, browsers automatically include the stored credentials with every request to the device's origin. This design flaw allows attackers to craft HTML forms or JavaScript-based requests that perform administrative actions on behalf of the authenticated user without their knowledge or consent.

The vulnerability enables attackers to manipulate critical device settings including RADIUS authentication accounts, network configurations, and diagnostic operations—all of which could compromise the security and operational integrity of industrial environments where these motion controllers are deployed.

Root Cause

The root cause of this vulnerability is the absence of anti-CSRF protection mechanisms in the setup.cgi endpoint. The firmware fails to implement standard CSRF defenses such as synchronizer tokens, same-site cookie attributes, or origin header validation. Combined with the use of HTTP Basic Authentication, which causes browsers to automatically transmit credentials, the device becomes susceptible to cross-origin request forgery attacks.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker must trick an authenticated administrator into visiting a malicious webpage while they have an active session with the Hereta ETH-IMC408M device. The malicious page can then submit hidden form submissions or XMLHttpRequests to the device's setup.cgi endpoint.

The attacker does not need direct network access to the device—they only need the victim to visit their controlled webpage while on the same network as the vulnerable controller. This makes the attack particularly dangerous in environments where administrators regularly browse the internet from workstations that have access to industrial control networks.

For detailed technical analysis of the exploitation mechanism, refer to the VulnCheck Hereta CSRF Advisory.

Detection Methods for CVE-2026-29521

Indicators of Compromise

• Unexpected changes to RADIUS account configurations on ETH-IMC408M devices
• Unauthorized modifications to network settings without administrator action
• Unexpected diagnostic operations or system resets logged on the device
• Web server logs showing POST requests to setup.cgi originating from external referrers

Detection Strategies

• Monitor HTTP request logs on Hereta ETH-IMC408M devices for configuration changes with suspicious or missing Referer headers
• Implement network intrusion detection rules to alert on POST requests to setup.cgi containing configuration modification parameters
• Deploy web application firewalls to inspect and potentially block cross-origin requests to the device management interface
• Establish baseline configurations for affected devices and alert on any deviations

Monitoring Recommendations

• Enable comprehensive logging on all Hereta ETH-IMC408M devices and forward logs to a centralized SIEM
• Configure alerting for any configuration changes outside of scheduled maintenance windows
• Monitor for unusual network traffic patterns between administrator workstations and industrial control devices
• Implement regular configuration audits to detect unauthorized modifications

How to Mitigate CVE-2026-29521

Immediate Actions Required

• Isolate Hereta ETH-IMC408M devices from networks where administrators may browse untrusted websites
• Implement network segmentation to restrict access to device management interfaces from trusted management VLANs only
• Require administrators to close all browser sessions before accessing device configuration pages
• Use dedicated management workstations with restricted internet access for industrial device administration

Patch Information

At the time of publication, no vendor patch has been identified for this vulnerability. Organizations should monitor the Archived Hereta Homepage and the VulnCheck Hereta CSRF Advisory for updates regarding firmware patches or vendor guidance.

Workarounds

• Deploy a reverse proxy with CSRF protection in front of the device's web interface
• Restrict access to the management interface via firewall rules to specific trusted IP addresses
• Use a separate browser or browser profile exclusively for device management that is never used for general web browsing
• Consider disabling the web management interface entirely if alternative configuration methods (serial console, dedicated management software) are available

# Example network segmentation configuration (iptables)
# Restrict access to Hereta ETH-IMC408M management interface
# Replace 192.168.1.100 with your device IP and 10.0.0.0/24 with your management network

iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -d 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -d 192.168.1.100 -j DROP