CVE-2025-27020: Nokia Infinera Mtc-9 Firmware RCE Flaw

CVE-2025-27020 Overview

CVE-2025-27020 is a critical authentication bypass vulnerability affecting the Nokia Infinera MTC-9 telecommunications equipment. The vulnerability stems from improper configuration of the SSH service, which allows unauthenticated attackers to execute arbitrary commands and access sensitive data on the device's file system remotely over the network.

This vulnerability represents a severe security risk for telecommunications infrastructure, as the MTC-9 is used in optical transport networks. An attacker exploiting this flaw could gain complete control over the affected device without requiring any authentication credentials.

Critical Impact

Unauthenticated remote attackers can execute arbitrary commands and access file system data on affected Infinera MTC-9 devices, potentially compromising critical telecommunications infrastructure.

Affected Products

• Nokia Infinera MTC-9 Firmware versions from R22.1.1.0275 before R23.0
• Nokia Infinera MTC-9 Hardware

Discovery Timeline

• 2025-12-08 - CVE-2025-27020 published to NVD
• 2025-12-22 - Last updated in NVD database

Technical Details for CVE-2025-27020

Vulnerability Analysis

This vulnerability is classified under CWE-306 (Missing Authentication for Critical Function). The SSH service on affected Infinera MTC-9 devices is improperly configured, failing to enforce authentication requirements for remote connections. This misconfiguration allows network-accessible attackers to connect to the SSH service and execute commands without providing valid credentials.

The attack can be executed remotely over the network without any user interaction or privileges required. Successful exploitation grants the attacker full access to execute arbitrary commands on the device, read and potentially modify file system data, and compromise the confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of CVE-2025-27020 is an insecure default configuration of the SSH service in the Infinera MTC-9 firmware. The SSH daemon fails to properly enforce authentication mechanisms, allowing connections to proceed without credential validation. This configuration error affects firmware versions starting from R22.1.1.0275 and prior to R23.0.

Attack Vector

The attack vector is network-based, requiring only network connectivity to the vulnerable SSH service. An attacker can exploit this vulnerability by initiating an SSH connection to an exposed Infinera MTC-9 device. Due to the missing authentication requirement, the attacker bypasses normal credential checks and gains command execution capabilities.

The exploitation process involves identifying an exposed MTC-9 device with the vulnerable SSH configuration, connecting to the SSH service on the standard port, and gaining command-line access without authentication. Once access is obtained, the attacker can execute arbitrary commands, exfiltrate configuration data, modify system settings, or use the compromised device as a pivot point for further network attacks.

Detection Methods for CVE-2025-27020

Indicators of Compromise

• Unexpected SSH connections to Infinera MTC-9 devices from unknown or unauthorized IP addresses
• Anomalous command execution patterns or unusual processes running on MTC-9 devices
• Unauthorized access to configuration files or sensitive data on the device file system
• Unexpected changes to device configurations or firmware settings

Detection Strategies

• Monitor network traffic for SSH connections to MTC-9 devices from external or unauthorized sources
• Implement IDS/IPS rules to detect unauthenticated SSH session establishment patterns
• Review SSH authentication logs for successful connections without proper credential exchange
• Deploy network segmentation monitoring to detect lateral movement from compromised devices

Monitoring Recommendations

• Enable comprehensive logging on all Infinera MTC-9 devices and forward logs to a central SIEM
• Establish baseline behavior for SSH connections and alert on deviations
• Implement continuous vulnerability scanning to identify devices running affected firmware versions
• Monitor for reconnaissance activities targeting SSH services on telecommunications infrastructure

How to Mitigate CVE-2025-27020

Immediate Actions Required

• Upgrade affected Infinera MTC-9 devices to firmware version R23.0 or later immediately
• Isolate vulnerable devices from untrusted networks until patching is complete
• Implement network access controls to restrict SSH access to authorized management networks only
• Audit affected devices for signs of compromise before and after patching

Patch Information

Nokia has addressed this vulnerability in Infinera MTC-9 firmware version R23.0. Organizations should upgrade to this version or later to remediate the vulnerability. For additional technical details, refer to the CVCN security advisory.

Workarounds

• Implement strict network segmentation to isolate MTC-9 devices from untrusted network segments
• Deploy firewall rules to restrict SSH access only to authorized management IP addresses
• Consider disabling the SSH service entirely if remote management is not required until patching is possible
• Implement VPN requirements for any remote access to device management interfaces

# Example firewall rule to restrict SSH access (adjust for your environment)
# Allow SSH only from trusted management network
iptables -A INPUT -p tcp --dport 22 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j DROP