CVE-2026-2491: Socomec DIRIS A-40 Auth Bypass Vulnerability

CVE-2026-2491 Overview

CVE-2026-2491 is an authentication bypass vulnerability affecting Socomec DIRIS A-40 power monitoring devices. This vulnerability allows network-adjacent attackers to bypass authentication on affected installations without requiring any prior authentication.

The specific flaw exists within the web API implementation, which listens on TCP port 80 by default. The issue results from the lack of authentication prior to allowing access to functionality (CWE-306: Missing Authentication for Critical Function). An attacker can leverage this vulnerability to bypass authentication on the system and gain unauthorized access to device functionality.

Critical Impact
Network-adjacent attackers can bypass authentication on Socomec DIRIS A-40 power monitoring devices, potentially gaining unauthorized access to critical infrastructure monitoring systems without any credentials.

Affected Products

Socomec DIRIS A-40 power monitoring devices
Devices with web API exposed on TCP port 80
Installations without network segmentation from adjacent networks

Discovery Timeline

2026-03-16 - CVE-2026-2491 published to NVD
2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-2491

Vulnerability Analysis

This authentication bypass vulnerability (CWE-306) represents a fundamental security design flaw in the Socomec DIRIS A-40 web API implementation. The device fails to implement proper authentication checks before granting access to sensitive functionality exposed through its HTTP API on TCP port 80.

Power monitoring devices like the DIRIS A-40 are commonly deployed in critical infrastructure environments including data centers, industrial facilities, and electrical distribution systems. Unauthorized access to these devices could allow attackers to manipulate power monitoring data, alter device configurations, or use the compromised device as a pivot point for further network intrusion.

The adjacent network attack vector requirement means attackers must be on the same network segment as the vulnerable device, which provides some limitation on the attack surface. However, in environments with flat network architectures or compromised network boundaries, this constraint may not provide adequate protection.

Root Cause

The root cause of this vulnerability is the complete absence of authentication mechanisms in the web API implementation. The API endpoints are accessible without any credential verification, allowing any network-adjacent attacker to interact with device functionality that should be restricted to authorized administrators only. This represents a Missing Authentication for Critical Function (CWE-306) weakness.

Attack Vector

The attack is conducted from an adjacent network position, requiring the attacker to have network-level access to the same segment as the target DIRIS A-40 device. Once positioned, the attacker can directly access the HTTP API on TCP port 80 without providing any authentication credentials.

The vulnerability can be exploited by sending crafted HTTP requests to the web API endpoints. Since no authentication is required, an attacker can enumerate and interact with available API endpoints to extract power monitoring data, modify device settings, or perform other administrative functions.

For detailed technical information about this vulnerability, refer to the Zero Day Initiative Advisory ZDI-26-129 and the Socomec Cyber Vulnerabilities Resource.

Detection Methods for CVE-2026-2491

Indicators of Compromise

Unusual HTTP traffic to DIRIS A-40 devices on TCP port 80 from unauthorized network segments
Unexpected API requests to power monitoring device endpoints
Configuration changes on DIRIS A-40 devices without corresponding administrative activity logs
Network reconnaissance activity targeting port 80 on industrial/ICS network segments

Detection Strategies

Implement network monitoring to detect HTTP traffic to DIRIS A-40 devices from non-administrative workstations
Deploy intrusion detection signatures to identify unauthenticated API access attempts
Monitor for network scanning activity targeting TCP port 80 on OT/ICS network segments
Establish baselines for normal API traffic patterns and alert on anomalies

Monitoring Recommendations

Enable and centralize logging for all DIRIS A-40 devices where supported
Implement network segmentation monitoring to detect attempts to access industrial network segments
Deploy network traffic analysis tools to identify unauthorized access to power monitoring devices
Correlate API access logs with administrative activity records to identify unauthorized actions

How to Mitigate CVE-2026-2491

Immediate Actions Required

Implement strict network segmentation to isolate DIRIS A-40 devices from general network access
Deploy firewall rules to restrict TCP port 80 access to authorized management stations only
Conduct an audit of all DIRIS A-40 device configurations to identify any unauthorized changes
Monitor the Socomec Cyber Vulnerabilities Resource for firmware updates and patches

Patch Information

Organizations should monitor Socomec's official security resources for firmware updates that address this vulnerability. Consult the Socomec Cyber Vulnerabilities Resource for the latest security advisories and available patches.

Additionally, review the Zero Day Initiative Advisory ZDI-26-129 for detailed vulnerability information and remediation guidance.

Workarounds

Place DIRIS A-40 devices behind a properly configured firewall or VPN that requires authentication
Implement network access control lists (ACLs) to restrict which hosts can communicate with the device
Consider disabling the web API if not required for operational purposes
Deploy a reverse proxy with authentication in front of the device's web interface

bash

# Example firewall rule to restrict access to DIRIS A-40 devices
# Allow only management workstation to access the device web API
iptables -A FORWARD -s 192.168.10.100 -d 192.168.20.50 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 192.168.20.50 -p tcp --dport 80 -j DROP