CVE-2025-41696 is a vulnerability identified in the Phoenix Contact FL SWITCH 2005 industrial network switch, categorized under CWE-798 for the use of hardcoded credentials. The vulnerability arises because the device contains an undocumented UART port on its printed circuit board (PCB) that can be accessed as a side-channel. An attacker with physical access to this UART port can leverage hardcoded user credentials, which were previously disclosed in CVE-2025-41692, to gain unauthorized read access to portions of the device's filesystem. This read access could potentially expose sensitive configuration files, credentials, or other critical data stored on the device. The CVSS v3.1 base score is 4.6, indicating medium severity, with the vector indicating that the attack requires physical access (AV:P), has low attack complexity (AC:L), requires no privileges (PR:N), no user interaction (UI:N), and impacts confidentiality only (C:H, I:N, A:N). The vulnerability does not allow modification or denial of service but compromises confidentiality by exposing sensitive information. No patches or fixes have been published yet, and no known exploits are reported in the wild. The vulnerability highlights the risks associated with embedded hardcoded credentials and undocumented hardware interfaces in industrial control devices, which can be leveraged by attackers with physical access to bypass logical security controls.

For European organizations, especially those operating critical infrastructure, manufacturing, or industrial automation environments, this vulnerability poses a risk of sensitive information disclosure. Attackers gaining read access to the filesystem could extract configuration data, network credentials, or other sensitive operational information, potentially facilitating further attacks or espionage. While the vulnerability does not directly impact system integrity or availability, the confidentiality breach could undermine trust in network security and lead to targeted attacks. The requirement for physical access limits the threat to environments where devices are not adequately secured against unauthorized personnel. However, in industrial settings where devices may be deployed in less physically secure locations, the risk increases. The exposure of hardcoded credentials could also enable lateral movement within the network if attackers combine this vulnerability with others. European organizations must consider the potential for industrial espionage, sabotage, or compliance violations due to unauthorized data access.

1. Physically secure all Phoenix Contact FL SWITCH 2005 devices to prevent unauthorized access to the UART port, including locking network cabinets and restricting access to authorized personnel only. 2. Implement strict access control and monitoring around industrial network equipment to detect and respond to any physical tampering attempts. 3. Use network segmentation to isolate vulnerable devices from critical network segments, limiting the impact of any compromise. 4. Monitor device logs and network traffic for unusual read or configuration access patterns that may indicate exploitation attempts. 5. Engage with Phoenix Contact for updates and patches addressing this vulnerability and plan timely deployment once available. 6. Consider replacing or upgrading devices with known hardcoded credential issues if patching is not feasible in the short term. 7. Conduct regular security audits and penetration tests focusing on physical security and embedded device vulnerabilities. 8. Educate operational technology (OT) staff about the risks of undocumented hardware interfaces and hardcoded credentials to improve detection and prevention.