CVE-2025-69981: FUXA v1.2.7 RCE Vulnerability

CVE-2025-69981 Overview

FUXA v1.2.7 contains an Unrestricted File Upload vulnerability in the /api/upload API endpoint. The endpoint lacks authentication mechanisms, allowing unauthenticated remote attackers to upload arbitrary files. This can be exploited to overwrite critical system files (such as the SQLite user database) to gain administrative access, or to upload malicious scripts to execute arbitrary code.

Critical Impact

Unauthenticated attackers can upload arbitrary files to compromise system integrity, overwrite the user database to gain administrative access, or achieve remote code execution through malicious script uploads.

Affected Products

• FUXA v1.2.7

Discovery Timeline

• 2026-02-03 - CVE CVE-2025-69981 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2025-69981

Vulnerability Analysis

This vulnerability represents an Unrestricted File Upload flaw combined with Missing Authentication, creating a critical attack surface in the FUXA SCADA/HMI web application. The /api/upload endpoint accepts file uploads without verifying the identity of the requester, meaning any network-accessible attacker can interact with this functionality.

The lack of authentication is compounded by the absence of file type validation, allowing attackers to upload files of any extension or content type. This enables multiple attack scenarios: overwriting the SQLite database file (users.db) to inject administrative credentials, uploading web shells or malicious scripts to achieve remote code execution, or replacing legitimate application files with trojaned versions.

FUXA is commonly deployed in industrial control system (ICS) and operational technology (OT) environments for SCADA visualization, making this vulnerability particularly concerning due to the potential impact on critical infrastructure.

Root Cause

The root cause stems from a design flaw in the /api/upload endpoint implementation. The API route handler processes incoming file uploads without implementing any authentication middleware or authorization checks. Additionally, there is no validation of uploaded file types, extensions, or content, allowing arbitrary files to be written to the server's filesystem. This combination of missing authentication and missing input validation creates a trivially exploitable attack vector.

Attack Vector

An attacker can exploit this vulnerability by sending crafted HTTP POST requests to the /api/upload endpoint. Since no authentication is required, the attacker only needs network access to the FUXA instance. The attack can proceed as follows:

1. The attacker identifies a FUXA instance exposed on the network (commonly on port 1881)
2. A POST request is sent to /api/upload with a malicious file payload
3. The file is written to the server without validation
4. Depending on the attacker's objective, they may overwrite the SQLite user database to gain admin access, or upload executable scripts for code execution

The vulnerability can be referenced in the FUXA server API implementation on GitHub for technical context on the affected code path.

Detection Methods for CVE-2025-69981

Indicators of Compromise

• Unexpected files appearing in FUXA upload directories or application paths
• Modified users.db SQLite database with unauthorized administrative accounts
• Web shells or script files (.js, .php, .sh) in application directories
• Anomalous HTTP POST requests to /api/upload from external or unauthorized IP addresses

Detection Strategies

• Monitor HTTP access logs for POST requests to the /api/upload endpoint, especially from unauthenticated sessions or external networks
• Implement file integrity monitoring (FIM) on FUXA application directories to detect unauthorized file modifications
• Deploy network intrusion detection rules to flag upload requests containing suspicious file extensions or content patterns
• Audit the SQLite user database for unexpected account creation or privilege modifications

Monitoring Recommendations

• Enable verbose logging on the FUXA application to capture all API interactions
• Configure SIEM alerts for multiple upload attempts from the same source in a short time window
• Monitor for process execution anomalies on the FUXA host that may indicate uploaded scripts being executed
• Implement network segmentation to limit exposure of FUXA instances to untrusted networks

How to Mitigate CVE-2025-69981

Immediate Actions Required

• Restrict network access to FUXA instances using firewall rules to allow only trusted IP addresses
• Place FUXA behind a reverse proxy with authentication enforcement
• Review and remove any suspicious files that may have been uploaded to the server
• Audit the user database for unauthorized accounts and reset administrative credentials

Patch Information

No official vendor patch information is available at this time. Organizations should monitor the FUXA GitHub repository for security updates and new releases that address this vulnerability.

Workarounds

• Implement network-level access controls to restrict access to the /api/upload endpoint to authorized hosts only
• Deploy a Web Application Firewall (WAF) with rules to block unauthenticated upload requests
• Consider disabling the upload functionality if not required for operations until a patch is available
• Run FUXA in an isolated network segment with no direct internet exposure

Network isolation is critical for FUXA deployments, especially in ICS/OT environments. Ensure that the application is not directly accessible from the internet and that access is controlled through VPN or jump servers with proper authentication.