CVE-2025-67039: Lantronix EDS3000PS Auth Bypass Flaw

CVE-2025-67039 Overview

An authentication bypass vulnerability has been discovered in the Lantronix EDS3000PS device server. The flaw allows unauthenticated remote attackers to bypass authentication controls on management pages by appending a specific suffix to the URL and sending an Authorization header with "admin" as the username. This vulnerability enables attackers to gain unauthorized administrative access to the device without valid credentials.

Critical Impact

Remote attackers can bypass authentication controls and gain full administrative access to Lantronix EDS3000PS devices, potentially compromising sensitive industrial control system environments.

Affected Products

• Lantronix EDS3000PS version 3.1.0.0R2

Discovery Timeline

• 2026-03-11 - CVE CVE-2025-67039 published to NVD
• 2026-03-12 - Last updated in NVD database

Technical Details for CVE-2025-67039

Vulnerability Analysis

This vulnerability is classified as CWE-288 (Authentication Bypass Using an Alternate Path or Channel). The Lantronix EDS3000PS device server implements a flawed authentication mechanism that can be circumvented through URL manipulation combined with a crafted HTTP Authorization header.

The root issue lies in the web management interface's authentication validation logic. When certain URL suffixes are appended to management page requests, the authentication check is improperly bypassed. Additionally, the system accepts an Authorization header containing "admin" as the username without properly validating the corresponding password or session credentials.

This combination of weaknesses allows an unauthenticated attacker to access protected management functionality that should require valid administrator credentials. The attack can be executed remotely over the network without any prior authentication or user interaction.

Root Cause

The vulnerability stems from improper authentication validation in the web management interface. The authentication mechanism fails to properly enforce access controls when specific URL patterns are encountered, allowing alternate paths to bypass the intended security checks. This represents a fundamental flaw in how the device validates administrative access requests.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a target Lantronix EDS3000PS device exposed on the network
2. Crafting an HTTP request to a management page with a specific URL suffix
3. Including an Authorization header with "admin" as the username value
4. Gaining unauthorized access to administrative management functions

The exploitation mechanism involves URL manipulation combined with HTTP header injection. Attackers can access protected management pages by appending specific suffixes to URLs while providing a minimal Authorization header. This bypasses the normal authentication flow and grants administrative access. For detailed technical information, refer to the CISA ICS Advisory ICSA-26-069-02.

Detection Methods for CVE-2025-67039

Indicators of Compromise

• Unusual HTTP requests to management pages with non-standard URL suffixes
• Authorization headers containing "admin" username without corresponding valid session tokens
• Unexpected administrative configuration changes on EDS3000PS devices
• Access to management interfaces from unauthorized IP addresses

Detection Strategies

• Monitor HTTP traffic to EDS3000PS devices for requests with anomalous URL patterns
• Implement web application firewall rules to detect and block requests with suspicious URL suffixes targeting management endpoints
• Review authentication logs for failed or bypassed authentication attempts
• Deploy network intrusion detection signatures for known authentication bypass patterns

Monitoring Recommendations

• Enable detailed logging on EDS3000PS devices and forward logs to a SIEM solution
• Monitor for configuration changes made without corresponding legitimate administrator sessions
• Implement network segmentation to limit exposure of device management interfaces
• Establish baseline behavior for administrative access patterns and alert on deviations

How to Mitigate CVE-2025-67039

Immediate Actions Required

• Restrict network access to EDS3000PS management interfaces using firewall rules and network segmentation
• Place affected devices behind VPN or other secure access controls
• Monitor devices for signs of unauthorized access or configuration changes
• Review and audit current device configurations for any unauthorized modifications

Patch Information

Consult the Lantronix Official Site for firmware updates and security advisories addressing this vulnerability. The CISA ICS Advisory ICSA-26-069-02 provides additional guidance on mitigation measures for this vulnerability in industrial control system environments.

Workarounds

• Implement network-level access controls to restrict management interface access to authorized IP addresses only
• Deploy a reverse proxy with additional authentication in front of the device management interface
• Disable or block remote access to management pages if not operationally required
• Use a jump server or bastion host for administrative access to reduce direct exposure

# Example: Restrict management interface access using iptables
# Allow only specific trusted management IP to access device on port 80/443
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP