CVE-2026-2403: Log Truncation Vulnerability via Input

CVE-2026-2403 Overview

CVE-2026-2403 is an Improper Validation of Specified Quantity in Input vulnerability (CWE-1284) that exists in the web administration interface of affected Schneider Electric products. The vulnerability could cause Event and Data Log truncation, impacting log integrity when a Web Admin user alters the POST /logsettings request payload.

Critical Impact

Exploitation of this vulnerability allows authenticated attackers to manipulate log settings, potentially truncating event and data logs. This can compromise audit trail integrity and forensic investigation capabilities.

Affected Products

• Schneider Electric products with Web Admin interface (refer to SEVD-2026-104-01 for specific product versions)

Discovery Timeline

• April 14, 2026 - CVE-2026-2403 published to NVD
• April 14, 2026 - Last updated in NVD database

Technical Details for CVE-2026-2403

Vulnerability Analysis

This vulnerability stems from insufficient validation of quantity-based input parameters within the web administration interface. When processing log configuration requests, the application fails to properly validate the specified quantity values in the POST /logsettings endpoint. This allows an authenticated Web Admin user to submit manipulated payload values that fall outside expected boundaries, leading to unintended log truncation behavior.

The impact of this vulnerability is primarily on log integrity. Event logs and data logs serve critical functions in security monitoring, compliance auditing, and incident investigation. By truncating these logs, an attacker could potentially hide malicious activities or disrupt forensic analysis capabilities within the affected system.

Root Cause

The root cause of CVE-2026-2403 is the improper validation of specified quantity parameters in the input processing logic for the /logsettings endpoint. The application accepts and processes quantity values without adequate boundary checking or type validation, allowing malformed or out-of-range values to be processed. This falls under CWE-1284: Improper Validation of Specified Quantity in Input.

Attack Vector

The attack is network-based and requires authenticated access with Web Admin privileges. An attacker must first obtain valid credentials for a Web Admin account, then craft a malicious POST request to the /logsettings endpoint with manipulated payload values. The altered request can specify quantity parameters that cause the system to truncate existing event and data logs.

The exploitation process involves intercepting or crafting HTTP POST requests to the log settings configuration endpoint and modifying the quantity fields to trigger the truncation behavior. Since this requires Web Admin authentication, the attack surface is limited to authenticated users with administrative privileges, either through compromised credentials or insider threat scenarios.

Detection Methods for CVE-2026-2403

Indicators of Compromise

• Unexpected modifications to log settings or log retention configurations
• Sudden truncation or gaps in event and data logs
• Unusual POST requests to /logsettings endpoints with atypical payload values
• Authentication events for Web Admin accounts followed by configuration changes

Detection Strategies

• Monitor and alert on all configuration changes to logging settings in affected Schneider Electric products
• Implement web application firewall (WAF) rules to detect anomalous POST requests to /logsettings with unusual parameter values
• Enable detailed audit logging for all administrative actions, storing logs externally to prevent local tampering
• Review Web Admin account access logs for suspicious authentication patterns or unauthorized access attempts

Monitoring Recommendations

• Centralize and forward logs to a SIEM solution to maintain log integrity even if local logs are truncated
• Establish baselines for normal log settings configuration and alert on deviations
• Implement file integrity monitoring on log storage locations to detect unexpected changes
• Regularly review admin user activity and access patterns for anomalies

How to Mitigate CVE-2026-2403

Immediate Actions Required

• Review the Schneider Electric Security Notice SEVD-2026-104-01 for specific patch and remediation guidance
• Audit all Web Admin accounts and ensure only authorized personnel have access
• Implement strong authentication mechanisms including multi-factor authentication for administrative access
• Review recent log settings changes and verify log integrity

Patch Information

Schneider Electric has released security guidance for this vulnerability. Refer to the official Schneider Electric Security Notice SEVD-2026-104-01 for specific patch versions, affected product details, and recommended remediation steps.

Workarounds

• Restrict network access to the web administration interface using firewall rules or network segmentation
• Implement additional access controls to limit who can modify log settings
• Forward all logs to an external, centralized logging system immediately upon generation to preserve log integrity
• Enable additional monitoring and alerting on administrative interface activity until patches can be applied

# Example: Network access restriction for admin interface
# Restrict access to admin interface to trusted management networks only
iptables -A INPUT -p tcp --dport 443 -s 10.0.100.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP