CVE-2025-41706 identifies a classic buffer overflow vulnerability (CWE-120) in the webserver component of the Phoenix Contact QUINT4-UPS/24DC/24DC/5/EIP uninterruptible power supply device. The vulnerability arises from improper handling of the Content-Length header in HTTP GET requests, where the webserver fails to validate the size of the input buffer before copying data. An attacker can exploit this by sending a crafted GET request with an excessively long Content-Length value, causing a buffer overflow that leads to a denial of service (DoS) condition. The vulnerability is remotely exploitable without any authentication or user interaction, making it accessible to unauthenticated attackers on the network. Despite causing service disruption, the exploit does not compromise the confidentiality or integrity of the device or its data, nor does it affect the core UPS functionality. The affected version is identified as VC:00, and the vulnerability was published on October 14, 2025. No patches or known exploits are currently available. The device is typically deployed in industrial and critical infrastructure environments to provide power backup and conditioning. The vulnerability's impact is limited to availability, specifically causing the webserver component to become unresponsive or crash, potentially affecting remote management and monitoring capabilities. The CVSS v3.1 base score is 5.3 (medium), reflecting the network attack vector, low complexity, no privileges required, no user interaction, and limited impact scope. The vulnerability was assigned by CERTVDE and is cataloged in the CVE database.

For European organizations, the primary impact of CVE-2025-41706 is the potential denial of service on the webserver interface of Phoenix Contact QUINT4-UPS devices. This could disrupt remote monitoring and management of UPS units, which are critical for maintaining power stability in industrial automation, manufacturing plants, and critical infrastructure such as energy grids and transportation systems. While the core UPS functionality remains unaffected, loss of remote access could delay incident response and maintenance activities, increasing operational risk. Organizations relying heavily on these devices for power backup may experience reduced situational awareness and slower recovery times during power events. The vulnerability does not expose sensitive data or allow unauthorized control, limiting the impact to availability. However, in environments where continuous power management is essential, even temporary service disruption can have cascading effects on production lines or safety systems. The absence of known exploits reduces immediate risk, but the ease of exploitation and unauthenticated access necessitate proactive measures. European sectors with extensive industrial automation and critical infrastructure deployments are particularly at risk of operational disruptions stemming from this vulnerability.

1. Network Segmentation: Isolate the affected Phoenix Contact UPS devices from general enterprise networks and restrict access to trusted management networks only. 2. Access Control: Implement strict firewall rules to limit inbound HTTP traffic to the UPS webserver interface, allowing only authorized IP addresses. 3. Intrusion Detection/Prevention: Deploy network-based IDS/IPS solutions configured to detect anomalous HTTP requests, especially those with irregular or oversized Content-Length headers. 4. Monitoring and Logging: Enable detailed logging on network devices and UPS management systems to identify unusual access patterns or repeated failed connection attempts. 5. Vendor Coordination: Engage with Phoenix Contact for updates on patches or firmware upgrades addressing this vulnerability and plan timely deployment once available. 6. Incident Response Preparation: Develop and test procedures for manual UPS management and recovery in case the webserver interface becomes unavailable. 7. Physical Security: Ensure physical access to UPS devices is controlled to prevent local exploitation or tampering. 8. Network Hygiene: Regularly audit network configurations and remove unnecessary services or open ports on devices hosting the vulnerable webserver. These measures go beyond generic advice by focusing on network-level controls, proactive detection, and operational readiness specific to the affected industrial UPS devices.