CVE-2025-27458 identifies a cryptographic vulnerability in the VNC authentication mechanism used by the Endress+Hauser MEAC300-FNADE4 device. The authentication relies on a challenge-response protocol where both the client and server share the same password. The server sends a challenge to the client, which the client encrypts using the shared password and returns. The server then performs the same encryption locally and compares the results to authenticate the client. However, the entire VNC communication, including the challenge and response, is transmitted unencrypted. This allows an attacker with network access to intercept the challenge and response messages. Because the encryption algorithm used is considered broken or risky (CWE-327), an attacker can analyze the intercepted data to derive the shared password. Once the password is recovered, the attacker can gain unauthorized access to the device via VNC. The vulnerability affects all versions of the MEAC300-FNADE4 product. The CVSS v3.1 score is 6.5 (medium severity), reflecting that the attack can be performed remotely without privileges but requires user interaction (likely to initiate the connection). The vulnerability impacts confidentiality but does not affect integrity or availability. No patches are currently available, and no known exploits have been reported in the wild. The root cause is the use of a weak cryptographic algorithm combined with unencrypted communication, which together enable password recovery through passive network interception.

For European organizations using the Endress+Hauser MEAC300-FNADE4 devices, this vulnerability poses a significant risk to the confidentiality of device credentials and potentially sensitive operational data. These devices are typically deployed in industrial environments such as manufacturing plants, utilities, and process control systems. An attacker who recovers the VNC password can gain unauthorized remote access to the device, potentially allowing espionage, unauthorized monitoring, or preparation for further attacks on industrial control systems. While the vulnerability does not directly impact system integrity or availability, unauthorized access could be leveraged to disrupt operations indirectly. The risk is heightened in environments where network segmentation is weak or where the devices are accessible from less secure network zones. Given the critical role of industrial automation in European infrastructure and manufacturing sectors, exploitation could lead to operational disruptions and data breaches, impacting business continuity and regulatory compliance (e.g., GDPR for data confidentiality).

1. Network Segmentation: Isolate MEAC300-FNADE4 devices on dedicated, secured network segments with strict access controls to limit exposure to untrusted networks. 2. Use VPN or Encrypted Tunnels: Since VNC communication is unencrypted, implement VPNs or secure tunnels (e.g., SSH tunnels) to protect VNC traffic from interception. 3. Disable VNC Access: Where possible, disable VNC access to the device or restrict it to trusted management hosts. 4. Strong Password Policies: Enforce strong, complex passwords for VNC authentication to increase the difficulty of password derivation. 5. Monitor Network Traffic: Deploy intrusion detection systems to monitor for suspicious VNC traffic or repeated authentication attempts. 6. Vendor Engagement: Engage with Endress+Hauser for updates or patches addressing this vulnerability and plan for timely deployment once available. 7. Alternative Access Methods: Consider using more secure remote access methods that employ modern cryptographic protocols. 8. User Training: Educate network and security teams about the risks of unencrypted VNC and the importance of secure remote access configurations.