CVE-2025-41706 identifies a classic buffer overflow vulnerability (CWE-120) in the embedded webserver of Phoenix Contact's QUINT4-UPS/24DC/24DC/5/EIP power supply units. The vulnerability exists because the webserver fails to properly validate the size of the Content-Length header in incoming HTTP GET requests. An attacker can craft a GET request with an over-long Content-Length value, causing the server to copy data beyond the allocated buffer boundaries. This results in a denial of service (DoS) condition by crashing or destabilizing the webserver component. The vulnerability does not affect the core UPS functionality, meaning the power supply continues to operate normally, but remote management or monitoring via the web interface becomes unavailable. Exploitation requires no authentication or user interaction and can be performed remotely over the network, increasing the attack surface. The affected product version is VC:00, and no patches have been released at the time of publication. Although no known exploits are reported in the wild, the vulnerability's presence in critical industrial equipment raises concerns for operational continuity. The CVSS v3.1 base score is 5.3, reflecting medium severity due to the lack of confidentiality or integrity impact and the limited scope of the DoS effect. The issue was reserved in April 2025 and published in October 2025 by CERTVDE. Organizations relying on Phoenix Contact's QUINT4-UPS devices for industrial power supply and monitoring should be aware of this vulnerability and prepare to implement mitigations or updates once available.

The primary impact of CVE-2025-41706 is a denial of service condition on the embedded webserver of the affected Phoenix Contact UPS devices. For European organizations, especially those in industrial automation, manufacturing, energy, and critical infrastructure sectors, this could disrupt remote monitoring and management capabilities of power supply units. While the core UPS functionality remains unaffected, loss of webserver availability can delay incident response, reduce situational awareness, and complicate maintenance operations. In environments where centralized monitoring is critical for operational safety and uptime, such disruptions could lead to increased downtime or delayed detection of power issues. Additionally, repeated exploitation attempts could generate network noise or trigger cascading failures in monitoring systems. The vulnerability's unauthenticated remote exploitability increases risk, as attackers do not need credentials or user interaction. Given the widespread use of Phoenix Contact products in European industrial sectors, the operational impact could be significant if exploited at scale or combined with other attack vectors targeting industrial control systems.

Until an official patch is released by Phoenix Contact, European organizations should implement the following mitigations: 1) Restrict network access to the UPS webserver interfaces by placing them behind firewalls or network segmentation zones limiting exposure to trusted management networks only. 2) Deploy web application firewalls (WAFs) or intrusion prevention systems (IPS) configured to detect and block anomalous HTTP requests, specifically those with abnormally large Content-Length headers or malformed GET requests. 3) Monitor network traffic to and from UPS devices for unusual patterns or repeated malformed requests indicative of exploitation attempts. 4) Implement strict access control policies and disable webserver interfaces if remote management is not essential. 5) Maintain up-to-date asset inventories to quickly identify affected devices and prioritize remediation. 6) Engage with Phoenix Contact support channels to obtain patches or firmware updates as soon as they become available and plan for timely deployment. 7) Conduct regular vulnerability assessments and penetration tests focusing on industrial control system components to detect similar weaknesses proactively.