CVE-2025-69971: FUXA Auth Bypass Vulnerability

CVE-2025-69971 Overview

CVE-2025-69971 is a hard-coded credential vulnerability affecting FUXA v1.2.7, an open-source web-based process visualization (SCADA/HMI) software. The vulnerability exists in the server/api/jwt-helper.js file, where the application uses a hard-coded secret key to sign and verify JWT (JSON Web Token) tokens. This critical security flaw allows remote attackers to forge valid admin tokens and bypass authentication mechanisms, ultimately gaining full administrative access to the FUXA system.

Critical Impact

Remote attackers can forge valid JWT tokens using the hard-coded secret key, bypassing authentication entirely and gaining full administrative control over the FUXA SCADA/HMI system.

Affected Products

• FUXA v1.2.7
• Potentially earlier versions of FUXA using the same JWT implementation

Discovery Timeline

• 2026-02-03 - CVE-2025-69971 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2025-69971

Vulnerability Analysis

This vulnerability falls under the Hardcoded Credentials category (CWE-798), representing a fundamental security anti-pattern in software development. The FUXA application implements JWT-based authentication for its web interface, but critically fails to implement secure key management practices.

When JWT tokens are signed with a predictable or hard-coded secret key, the entire authentication mechanism becomes compromised. Attackers who discover or extract this hard-coded secret can create arbitrary JWT tokens with any claims they desire, including administrative privileges. This effectively renders the authentication system useless, as there is no way to distinguish between legitimate and forged tokens.

The impact is particularly severe for FUXA deployments because SCADA/HMI systems often control critical industrial processes. Unauthorized administrative access could allow attackers to manipulate process visualizations, alter configurations, or potentially affect connected industrial control systems.

Root Cause

The root cause of CVE-2025-69971 lies in the insecure implementation of JWT token management within the jwt-helper.js file. Instead of generating a unique, cryptographically secure secret key during installation or reading from a secure configuration source, the developers embedded a static secret key directly in the source code.

This hard-coded secret is used for both signing tokens during user authentication and verifying tokens during subsequent requests. Since the source code is publicly available on GitHub, any attacker can extract this secret and use it to forge tokens without needing valid credentials.

Attack Vector

The attack vector for this vulnerability is network-based and requires no prior authentication. An attacker can exploit this vulnerability through the following approach:

1. Secret Key Extraction: The attacker examines the publicly available source code in the GitHub JWT Helper Script to extract the hard-coded JWT secret key

2. Token Forging: Using the extracted secret, the attacker crafts a JWT token containing administrative claims (such as admin role or elevated permissions)

3. Authentication Bypass: The attacker sends requests to the FUXA application with the forged JWT token in the authorization header

4. Administrative Access: The application validates the token using the same hard-coded secret and grants full administrative access to the attacker

This attack can be performed remotely against any FUXA instance accessible over the network, making it particularly dangerous for internet-exposed deployments.

Detection Methods for CVE-2025-69971

Indicators of Compromise

• Unexpected JWT tokens appearing in server logs with claims inconsistent with legitimate user activity
• Authentication events from IP addresses not associated with known administrators
• Multiple administrative sessions originating from different geographic locations simultaneously
• Configuration changes or data access patterns that don't match expected administrative workflows

Detection Strategies

• Implement application-level logging to capture all JWT token validations and track anomalous authentication patterns
• Monitor for authentication attempts from unexpected source IP addresses or geographic regions
• Deploy web application firewall (WAF) rules to detect suspicious authorization header patterns
• Review server access logs for unusual administrative API endpoint access

Monitoring Recommendations

• Enable comprehensive audit logging for all administrative actions within the FUXA application
• Set up alerts for configuration changes performed outside of maintenance windows
• Monitor network traffic for unusual volumes of API requests to administrative endpoints
• Implement session tracking to identify multiple concurrent admin sessions from disparate locations

How to Mitigate CVE-2025-69971

Immediate Actions Required

• Restrict network access to FUXA instances, limiting exposure to trusted networks only
• Place FUXA deployments behind a VPN or implement additional network-level authentication
• Review access logs for any signs of unauthorized administrative access
• Consider taking internet-facing FUXA instances offline until a patch or workaround is implemented

Patch Information

At the time of publication, users should monitor the official FUXA repository and release channels for security updates addressing this vulnerability. Check the GitHub JWT Helper Script for any commits that implement dynamic secret key generation or secure key management.

Until an official patch is released, organizations should implement the workarounds described below and consider the risk level appropriate for their deployment environment.

Workarounds

• Modify the jwt-helper.js file to use an environment variable or external configuration file for the JWT secret instead of the hard-coded value
• Generate a cryptographically secure random string (minimum 256 bits) to replace the hard-coded secret
• Implement network segmentation to isolate FUXA from untrusted networks
• Deploy an authenticating reverse proxy in front of FUXA to add an additional layer of authentication

# Example: Generate a secure random secret and set as environment variable
# Generate a 64-character random secret
export FUXA_JWT_SECRET=$(openssl rand -base64 48)

# Ensure the environment variable is set before starting FUXA
# Modify jwt-helper.js to read from process.env.FUXA_JWT_SECRET