CVE-2026-1626: Sick Lms1000 Information Disclosure Issue

CVE-2026-1626 Overview

CVE-2026-1626 is a cryptographic vulnerability affecting SICK industrial sensors, specifically the LMS1000 and MRS1000 product lines. The vulnerability stems from the use of weak CBC-based cipher suites in the devices' SSH service, allowing attackers with network access to potentially observe or manipulate encrypted SSH communications.

This vulnerability is particularly concerning in industrial control system (ICS) environments where SICK LiDAR sensors are commonly deployed for safety-critical applications including collision avoidance, area monitoring, and automated material handling systems.

Critical Impact

Attackers who can intercept network traffic may decrypt or manipulate SSH communications to the affected devices, potentially leading to unauthorized configuration changes or exposure of sensitive operational data.

Affected Products

• SICK LMS1000 Firmware (all versions)
• SICK LMS1000 Hardware
• SICK MRS1000 Firmware (all versions)
• SICK MRS1000 Hardware

Discovery Timeline

• 2026-02-27 - CVE-2026-1626 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-1626

Vulnerability Analysis

This vulnerability is classified under CWE-327 (Use of a Broken or Risky Cryptographic Algorithm). The affected SICK devices implement SSH services that support CBC (Cipher Block Chaining) mode cipher suites, which are known to be susceptible to certain cryptographic attacks.

CBC mode ciphers in SSH are vulnerable to plaintext recovery attacks when an adversary can observe and manipulate network traffic. In the context of industrial devices like the LMS1000 and MRS1000 LiDAR sensors, this could enable attackers to intercept device configuration commands, authentication credentials, or operational data transmitted over SSH sessions.

The vulnerability requires network-level access to intercept SSH traffic, but does not require prior authentication to the device itself. An attacker positioned on the same network segment or with man-in-the-middle capabilities could exploit this weakness.

Root Cause

The root cause is the implementation of weak CBC-based cipher suites in the SSH service configuration of the affected firmware. Modern SSH implementations should prioritize authenticated encryption modes such as AES-GCM or ChaCha20-Poly1305, which provide both confidentiality and integrity protection. The continued support for CBC mode ciphers creates an exploitable cryptographic weakness.

Attack Vector

The attack requires network access to intercept SSH communications between a management client and the affected SICK device. An attacker can leverage known CBC mode vulnerabilities to:

1. Position themselves on the network path between the SSH client and the SICK device
2. Capture encrypted SSH packets using the weak CBC cipher suite
3. Apply cryptographic attacks against the CBC mode encryption
4. Potentially recover portions of plaintext data or inject malicious commands

The attack is network-based and can be conducted without any prior authentication, making it particularly dangerous in environments where network segmentation is not properly implemented.

Detection Methods for CVE-2026-1626

Indicators of Compromise

• Unexpected SSH connection attempts to SICK LMS1000 or MRS1000 devices from unauthorized IP addresses
• ARP spoofing or MAC address anomalies on network segments containing SICK sensors
• Unusual network traffic patterns indicating man-in-the-middle positioning near industrial sensor devices
• Configuration changes to SICK devices that were not authorized through change management processes

Detection Strategies

• Deploy network intrusion detection systems (NIDS) to monitor for SSH traffic anomalies and potential MITM attack indicators
• Implement continuous monitoring for SSH cipher suite negotiation to detect when CBC-mode ciphers are being used
• Configure network monitoring tools to alert on ARP cache poisoning or suspicious layer 2 activity near critical OT devices
• Review SSH connection logs on management workstations for connections to SICK devices using weak cipher suites

Monitoring Recommendations

• Enable detailed logging on network infrastructure components to capture SSH session metadata
• Monitor for unauthorized devices appearing on OT network segments containing SICK sensors
• Implement network traffic analysis to baseline normal SSH behavior and alert on deviations
• Consider deploying industrial-grade network monitoring solutions that understand ICS protocols and device behaviors

How to Mitigate CVE-2026-1626

Immediate Actions Required

• Review the SICK CSAF Security Advisory for specific firmware update information
• Isolate affected SICK LMS1000 and MRS1000 devices on dedicated network segments with strict access controls
• Implement network-level encryption such as IPsec VPN tunnels for SSH communications to affected devices
• Disable SSH access if not operationally required, using alternative secure management methods where possible

Patch Information

SICK has released security advisories addressing this vulnerability. Administrators should consult the SICK PSIRT page for the latest firmware updates and detailed remediation guidance. The SICK Cybersecurity Operating Guidelines provide additional hardening recommendations for industrial deployments.

For ICS environments, follow the CISA ICS Recommended Practices when implementing security controls around these devices.

Workarounds

• Place affected SICK devices behind firewalls or jump servers that enforce strong cipher suites for SSH connections
• Implement network segmentation to limit exposure of SSH services to authorized management stations only
• Use VPN tunnels or other encrypted transport to protect SSH traffic at the network layer
• Configure SSH clients to only negotiate strong cipher suites (AES-GCM, ChaCha20-Poly1305) when connecting to management interfaces
• Consider disabling SSH entirely on affected devices and using alternative secure configuration methods if available