CVE-2026-4901: Hydrosystem Control System Info Disclosure

CVE-2026-4901 Overview

CVE-2026-4901 is a Sensitive Data Exposure vulnerability affecting Hydrosystem Control System. The system improperly saves sensitive information, including user credentials, into log files. This information leakage creates a significant security risk as attackers who gain access to these log files can obtain valid credentials and use them to gain further authorized access into the system. The vulnerability is particularly concerning when combined with CVE-2026-34184, which may allow unauthorized users to access these sensitive log files.

Critical Impact

User credentials logged in plaintext enable attackers to obtain authorized access to the Hydrosystem Control System, potentially leading to full system compromise when combined with CVE-2026-34184.

Affected Products

• Hydrosystem Control System versions prior to 9.8.5

Discovery Timeline

• 2026-04-09 - CVE CVE-2026-4901 published to NVD
• 2026-04-09 - Last updated in NVD database

Technical Details for CVE-2026-4901

Vulnerability Analysis

This vulnerability falls under CWE-532 (Insertion of Sensitive Information into Log File), a common security flaw where applications inadvertently write sensitive data to log files without proper sanitization or protection. In the case of Hydrosystem Control System, user credentials are being written directly to log files during system operations, likely during authentication attempts or session management activities.

The network-accessible nature of this vulnerability means that an attacker with high privileges may be able to access these log files remotely. When combined with CVE-2026-34184, which appears to provide a pathway for unauthorized file access, the impact is significantly amplified—allowing even unauthenticated attackers to potentially harvest credentials from the exposed log files.

Root Cause

The root cause of this vulnerability is improper logging practices within the Hydrosystem Control System. The application fails to sanitize or mask sensitive information before writing to log files. Specifically, user credentials (likely usernames and passwords) are being logged during authentication or related operations. This represents a fundamental violation of secure coding principles, which dictate that sensitive data should never be written to logs in plaintext form.

Attack Vector

The attack vector for CVE-2026-4901 is network-based, requiring high privileges to exploit directly. An attacker would need to:

1. Gain access to the system where Hydrosystem Control System log files are stored
2. Read the log files containing sensitive credential information
3. Extract valid user credentials from the logged data
4. Use the harvested credentials to authenticate as legitimate users

When chained with CVE-2026-34184, the attack becomes more severe as an unauthorized user may gain the initial access needed to read the sensitive log files without requiring high privileges.

Detection Methods for CVE-2026-4901

Indicators of Compromise

• Unusual access patterns to log file directories or log management systems
• Evidence of log file exfiltration or unauthorized log file access in system audit logs
• Authentication attempts using credentials that may have been exposed through log file access
• Unexpected file read operations targeting application log directories

Detection Strategies

• Monitor file system access to log directories for unauthorized read operations
• Implement file integrity monitoring (FIM) on log file locations to detect tampering or exfiltration
• Review authentication logs for suspicious login patterns that may indicate credential reuse from exposed logs
• Deploy endpoint detection solutions to identify processes accessing log files outside normal operational parameters

Monitoring Recommendations

• Enable detailed audit logging for all file access operations on Hydrosystem Control System servers
• Configure SIEM rules to alert on bulk log file access or log file transfers
• Implement network monitoring to detect potential log file exfiltration attempts
• Establish baseline behavior for log file access and alert on deviations

How to Mitigate CVE-2026-4901

Immediate Actions Required

• Upgrade Hydrosystem Control System to version 9.8.5 or later immediately
• Review existing log files for sensitive credential information and securely delete or archive them
• Rotate all user credentials that may have been exposed in log files
• Restrict access to log file directories to only essential personnel and processes
• Implement additional network segmentation to limit access to systems running Hydrosystem Control System

Patch Information

This vulnerability has been addressed in Hydrosystem Control System version 9.8.5. Organizations should update to this version or later to remediate the vulnerability. For additional information, refer to the CERT Poland CVE-2026-4901 Post or the Hydro System Website.

Workarounds

• Implement strict access controls on log file directories to prevent unauthorized access
• Configure log rotation with short retention periods to minimize exposure window
• Deploy file access monitoring to detect and alert on unauthorized log file access
• Consider implementing log redaction or masking solutions until the patch can be applied
• Network segment systems running vulnerable versions to limit attacker access paths