CVE-2026-31927: Anviz CX7 Path Traversal Vulnerability

CVE-2026-31927 Overview

CVE-2026-31927 is a path traversal vulnerability in Anviz CX7 Firmware that allows authenticated users to upload malicious CSV files containing path traversal sequences. This enables attackers to overwrite arbitrary files on the system, including critical configuration files such as /etc/shadow. When combined with debug-setting changes, this vulnerability can be leveraged to gain unauthorized SSH access to the affected device.

Critical Impact

Authenticated attackers can overwrite arbitrary system files through malicious CSV uploads, potentially leading to full system compromise via unauthorized SSH access.

Affected Products

• Anviz CX7 Firmware (vulnerable versions not specified)

Discovery Timeline

• 2026-04-17 - CVE-2026-31927 published to NVD
• 2026-04-20 - Last updated in NVD database

Technical Details for CVE-2026-31927

Vulnerability Analysis

This vulnerability is classified under CWE-23 (Relative Path Traversal), affecting the CSV upload functionality within the Anviz CX7 firmware. The vulnerability exists in the file upload handler that processes CSV files, where insufficient validation of file paths allows authenticated users to escape the intended directory structure.

The vulnerability requires authentication to exploit, limiting the attack surface to users who have valid credentials on the device. However, once authenticated, the attacker can craft a malicious CSV file containing path traversal sequences (e.g., ../) that traverse outside the intended upload directory. This allows overwriting of any file on the filesystem that the web application process has write permissions to access.

The network-based attack vector combined with low attack complexity makes this vulnerability particularly concerning for organizations with Anviz CX7 devices exposed to potentially hostile network environments. The impact is primarily to system integrity, as arbitrary file overwrites can compromise system configuration and security controls.

Root Cause

The root cause is improper input validation in the CSV upload functionality. The application fails to properly sanitize or validate file paths contained within uploaded CSV data, allowing relative path traversal sequences to escape the intended directory boundaries. This is a classic CWE-23 vulnerability where user-supplied input containing path components is used directly in file system operations without adequate validation.

Attack Vector

The attack is executed over the network by an authenticated user. An attacker with valid credentials can upload a specially crafted CSV file through the firmware's web interface. The malicious CSV contains path traversal sequences that direct the file write operation to arbitrary locations on the filesystem.

A typical attack chain involves:

1. Authenticating to the Anviz CX7 web interface with valid credentials
2. Crafting a malicious CSV file containing path traversal sequences targeting /etc/shadow
3. Uploading the crafted CSV through the vulnerable upload functionality
4. Overwriting the shadow file with attacker-controlled content containing a known password hash
5. Enabling debug settings (if required) to activate SSH access
6. Connecting via SSH using the attacker-controlled credentials

For detailed technical information, refer to the CISA ICS Advisory.

Detection Methods for CVE-2026-31927

Indicators of Compromise

• Unexpected modifications to system files such as /etc/shadow or /etc/passwd
• CSV upload requests containing path traversal sequences like ../ in file paths or payloads
• Unusual SSH login attempts or successful authentications following web interface activity
• Debug mode being enabled without administrative approval

Detection Strategies

• Monitor web server access logs for CSV upload requests with suspicious path patterns
• Implement file integrity monitoring (FIM) on critical system files including /etc/shadow, /etc/passwd, and other authentication-related files
• Configure IDS/IPS rules to detect path traversal patterns in HTTP POST requests
• Alert on debug mode configuration changes in device logs

Monitoring Recommendations

• Enable comprehensive logging on Anviz CX7 devices and forward logs to a centralized SIEM
• Implement real-time alerting for authentication changes and new SSH sessions
• Monitor for outbound connections from Anviz devices to unexpected destinations
• Review user access logs regularly for anomalous behavior patterns

How to Mitigate CVE-2026-31927

Immediate Actions Required

• Restrict network access to Anviz CX7 devices to trusted management networks only
• Review and audit all user accounts with access to the device, removing unnecessary privileges
• Disable SSH access if not required for operations
• Implement network segmentation to isolate vulnerable devices from critical infrastructure
• Monitor devices for signs of compromise as outlined in detection strategies

Patch Information

Contact Anviz for firmware updates and security patches. Refer to the Anviz Contact Page for support inquiries. Additional technical details are available in the CISA ICS Advisory and the GitHub CSAF File.

Workarounds

• Place Anviz CX7 devices behind a firewall with strict access controls limiting connectivity to authorized IP addresses
• Disable or restrict the CSV upload functionality if it is not required for operations
• Implement a web application firewall (WAF) with rules to block path traversal patterns
• Ensure debug mode is disabled and restrict the ability to enable it to highly privileged administrators only