CVE-2026-4832: SNMP Hard-coded Credentials Vulnerability

CVE-2026-4832 Overview

A Use of Hard-coded Credentials vulnerability (CWE-798) exists in Schneider Electric devices that could allow unauthorized access to sensitive device information. The vulnerability is triggered when an unauthenticated attacker is able to interrogate the SNMP port using embedded credentials, potentially exposing critical device configuration and operational data.

Critical Impact

Unauthenticated attackers can exploit hard-coded credentials to access sensitive device information via SNMP, potentially leading to reconnaissance for further attacks or unauthorized monitoring of industrial control systems.

Affected Products

• Schneider Electric devices with SNMP functionality (refer to Schneider Electric Security Notice for specific product details)

Discovery Timeline

• 2026-04-14 - CVE-2026-4832 published to NVD
• 2026-04-14 - Last updated in NVD database

Technical Details for CVE-2026-4832

Vulnerability Analysis

This vulnerability stems from the use of hard-coded credentials embedded within the device firmware or configuration. The SNMP (Simple Network Management Protocol) service exposes these credentials, allowing an unauthenticated attacker on the network to query device information without proper authorization. SNMP is commonly used for network management and monitoring, making it a valuable target for attackers seeking to enumerate network assets or gather intelligence on industrial control systems.

The vulnerability is classified under CWE-798 (Use of Hard-coded Credentials), which represents a significant security weakness where authentication credentials are statically defined in source code, configuration files, or firmware. This practice eliminates the ability for administrators to change credentials and makes all deployed instances vulnerable to the same attack.

Root Cause

The root cause of this vulnerability is the inclusion of static, hard-coded credentials within the SNMP configuration of the affected Schneider Electric devices. These credentials cannot be modified by end users and remain constant across all deployments of the affected firmware versions. This design flaw violates secure development best practices that mandate the use of unique, configurable credentials for each device deployment.

Attack Vector

The attack vector for CVE-2026-4832 is network-based, requiring no authentication and no user interaction. An attacker with network access to the SNMP port (typically UDP port 161) can exploit this vulnerability by using the hard-coded community strings or credentials to query device information.

The attack flow involves:

1. Network reconnaissance to identify devices with exposed SNMP services
2. Attempting connections using common or known hard-coded credentials
3. Once authenticated, querying the SNMP Management Information Base (MIB) to extract sensitive device information
4. Using gathered information for further reconnaissance or targeted attacks against industrial control systems

Detection Methods for CVE-2026-4832

Indicators of Compromise

• Unusual SNMP query activity from unauthorized IP addresses targeting affected Schneider Electric devices
• Successful SNMP authentication events from external or untrusted network segments
• High volume of SNMP GET requests against device MIB tables
• Presence of known hard-coded community strings in network traffic captures

Detection Strategies

• Deploy network monitoring to detect SNMP traffic on UDP port 161 from unexpected sources
• Implement SNMP access logging and alert on successful authentications from non-management hosts
• Use intrusion detection systems (IDS) to identify SNMP enumeration patterns
• Monitor for bulk SNMP queries that may indicate data exfiltration attempts

Monitoring Recommendations

• Establish baseline SNMP traffic patterns and alert on deviations
• Configure network segmentation to restrict SNMP access to authorized management systems only
• Implement real-time alerting for SNMP authentication attempts from untrusted networks
• Review SNMP access logs regularly for signs of unauthorized queries

How to Mitigate CVE-2026-4832

Immediate Actions Required

• Restrict network access to SNMP ports (UDP 161, 162) using firewalls and access control lists
• Segment affected devices from untrusted network zones
• Disable SNMP services if not operationally required
• Monitor for exploitation attempts while awaiting vendor patches

Patch Information

Refer to the Schneider Electric Security Notice SEVD-2026-104-03 for specific patch availability and firmware update instructions. Contact Schneider Electric support for guidance on remediation for your specific product deployment.

Workarounds

• Implement strict network segmentation to isolate affected devices from untrusted networks
• Use firewall rules to whitelist only authorized management stations for SNMP access
• Consider using VPN tunnels for remote SNMP management to prevent credential exposure
• Deploy network-based intrusion prevention systems to block unauthorized SNMP queries

# Example firewall configuration to restrict SNMP access
# Allow SNMP only from authorized management station
iptables -A INPUT -p udp --dport 161 -s 10.0.1.100 -j ACCEPT
iptables -A INPUT -p udp --dport 161 -j DROP
iptables -A INPUT -p udp --dport 162 -s 10.0.1.100 -j ACCEPT
iptables -A INPUT -p udp --dport 162 -j DROP