CVE-2026-29513: Hereta ETH-IMC408M XSS Vulnerability

CVE-2026-29513 Overview

CVE-2026-29513 is a stored cross-site scripting (XSS) vulnerability affecting Hereta ETH-IMC408M firmware version 1.0.15 and prior releases. The vulnerability allows authenticated attackers to inject arbitrary JavaScript code by manipulating the Device Location field within the System Status interface. Due to the lack of proper input sanitization, malicious scripts persist in the application and execute in the browsers of other users viewing the affected status page.

Stored XSS vulnerabilities are particularly dangerous because the malicious payload persists on the server, affecting all users who access the compromised page without requiring additional attacker interaction.

Critical Impact

Authenticated attackers can inject persistent malicious JavaScript that executes in the context of other users' browsers, potentially enabling session hijacking, credential theft, or further attack propagation.

Affected Products

• Hereta ETH-IMC408M firmware version 1.0.15
• Hereta ETH-IMC408M firmware versions prior to 1.0.15

Discovery Timeline

• 2026-03-16 - CVE-2026-29513 published to NVD
• 2026-03-17 - Last updated in NVD database

Technical Details for CVE-2026-29513

Vulnerability Analysis

This stored cross-site scripting vulnerability (CWE-79) exists in the Hereta ETH-IMC408M industrial motion controller's web management interface. The vulnerability stems from insufficient input validation and output encoding in the Device Location field accessible through the System Status interface.

When an authenticated user submits data to the Device Location field, the application fails to sanitize or encode the input before storing it in the device configuration. Subsequently, when any user views the System Status page, the stored payload is rendered directly in the HTML response without proper escaping, causing the browser to execute the injected JavaScript code.

The network-accessible attack vector means that any authenticated user with access to the device configuration interface can exploit this vulnerability. While the requirement for prior authentication limits the attack surface, industrial control devices often have weak or default credentials, which may lower the practical barrier to exploitation.

Root Cause

The root cause of this vulnerability is the absence of input validation and output encoding in the web application handling the Device Location parameter. The firmware does not implement proper sanitization routines to strip or encode special characters such as <, >, ", and ' before storing user input. Additionally, when rendering the stored data on the System Status page, the application fails to apply HTML entity encoding, allowing script tags and event handlers to execute in the victim's browser context.

Attack Vector

The attack requires an authenticated attacker to access the device's web management interface and navigate to the configuration section where the Device Location field is editable. By injecting JavaScript code within this field—such as script tags or event handler attributes—the payload becomes permanently stored in the device configuration.

Once stored, the malicious script executes whenever any user (including administrators) views the System Status page. This could enable attackers to steal session cookies, capture credentials, redirect users to phishing sites, or perform actions on behalf of the victim within the device management interface.

The vulnerability is exploited through the System Status interface where the Device Location field accepts and renders unsanitized user input. Attackers can inject payloads containing JavaScript that will execute when other users view the status page. For detailed technical information, refer to the VulnCheck Advisory: Hereta XSS.

Detection Methods for CVE-2026-29513

Indicators of Compromise

• Presence of script tags, event handlers, or encoded JavaScript within the Device Location field in device configurations
• Unexpected or malicious content appearing in the System Status page source code
• Browser console errors or blocked script execution warnings when viewing the System Status interface
• Unusual network requests originating from sessions viewing the device management pages

Detection Strategies

• Implement web application firewall (WAF) rules to detect XSS payloads in HTTP requests targeting device configuration endpoints
• Monitor device configuration changes for fields containing HTML tags, JavaScript code, or encoded script content
• Deploy browser-based XSS protection mechanisms and Content Security Policy (CSP) headers where possible
• Review access logs for authenticated sessions making configuration changes to input fields

Monitoring Recommendations

• Enable detailed logging of all configuration changes on Hereta ETH-IMC408M devices
• Configure network monitoring to detect suspicious patterns in traffic to and from device management interfaces
• Establish baseline configurations and alert on unauthorized modifications to device settings
• Implement user activity monitoring for privileged accounts with device configuration access

How to Mitigate CVE-2026-29513

Immediate Actions Required

• Restrict network access to the Hereta ETH-IMC408M web management interface to trusted IP addresses only
• Review and audit current Device Location field values for any suspicious or malicious content
• Implement strong authentication controls and remove default credentials from all devices
• Place affected devices behind network segmentation controls to limit exposure

Patch Information

No vendor patch has been identified in the available CVE data. The Archived Hereta Website may contain additional vendor information. Organizations should monitor the VulnCheck Advisory: Hereta XSS for updates regarding remediation guidance.

Workarounds

• Implement network-level access controls (firewalls, VLANs) to restrict management interface access to authorized personnel only
• Deploy a reverse proxy with XSS filtering capabilities in front of the device management interface
• Disable or restrict access to the Device Location configuration field if not operationally required
• Use browser security extensions that block inline script execution when accessing the device interface

# Example: Network segmentation using iptables to restrict management access
# Allow access only from trusted management network (10.0.1.0/24)
iptables -A INPUT -p tcp --dport 80 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP