CVE-2025-41722 identifies a critical security weakness in Sauter's modulo 6 devices modu680-AS, specifically within the wsc server component that handles SOAP message authentication. The vulnerability arises from the use of a hard-coded certificate embedded in the device software, violating secure credential management principles (CWE-798). This hard-coded certificate is used to verify the authenticity of incoming SOAP messages, but because it is static and embedded, an attacker can remotely extract the associated private keys without any authentication or user interaction. The extraction of these private keys compromises the confidentiality of the device's cryptographic material, potentially allowing attackers to forge authenticated messages, impersonate legitimate devices, or intercept sensitive communications. The CVSS v3.1 score of 7.5 reflects the high impact on confidentiality, with no impact on integrity or availability. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The vulnerability affects all versions listed as 0.0.0, indicating possibly initial or baseline firmware versions. No patches or fixes are currently linked, and no known exploits have been reported in the wild, though the risk remains significant due to the ease of exploitation and sensitive nature of the private keys. This vulnerability is particularly concerning for environments relying on these devices for building automation, industrial control, or critical infrastructure, where trust in device authentication is paramount.

For European organizations, the exposure of private keys in Sauter modulo 6 devices can lead to severe confidentiality breaches. Attackers could impersonate legitimate devices or controllers, inject malicious commands, or intercept sensitive operational data. This undermines trust in automation systems and could facilitate further attacks on critical infrastructure such as HVAC, lighting, or security systems in commercial buildings, manufacturing plants, or public facilities. The lack of integrity or availability impact means systems may continue operating normally while compromised, increasing the risk of stealthy attacks. Organizations in sectors like manufacturing, energy, and facility management that deploy these devices are at heightened risk. The potential for lateral movement or escalation following key compromise could lead to broader network infiltration. Given the widespread use of Sauter products in Europe, the vulnerability poses a significant threat to operational security and data confidentiality.

Immediate mitigation should focus on eliminating the use of hard-coded certificates by replacing them with unique, securely generated certificates per device. Organizations should work with Sauter or authorized vendors to obtain firmware updates or patches that remove hard-coded credentials and implement proper key management practices. Network segmentation should be enforced to isolate modulo 6 devices from untrusted networks, limiting exposure to remote attackers. Monitoring network traffic for unusual SOAP message activity or unauthorized access attempts can help detect exploitation attempts. Where possible, implement additional authentication layers or VPN access controls for management interfaces. Conduct thorough audits of all deployed devices to identify vulnerable units and prioritize their remediation. If patches are unavailable, consider device replacement or disabling vulnerable services until secure updates are provided. Finally, integrate these devices into broader security incident response plans to rapidly address any compromise.