CVE-2025-41694 identifies a resource exhaustion vulnerability in the Phoenix Contact FL SWITCH 2005, a network switch commonly used in industrial environments. The flaw arises from the webshell interface's handling of commands: when a low privileged remote attacker sends an empty command consisting solely of whitespace, the server enters a blocking state, waiting indefinitely for additional input. This behavior leads to allocation of resources without limits or throttling, classified under CWE-770. The consequence is a denial-of-service condition where the webserver becomes unresponsive, potentially disrupting network management and control functions. The vulnerability requires only low privilege remote access and no user interaction, making exploitation relatively straightforward in environments where the webshell is exposed. The CVSS v3.1 score of 6.5 reflects a medium severity, emphasizing the impact on availability without compromising confidentiality or integrity. No patches or fixes have been published yet, and no known exploits have been reported in the wild. The vulnerability was reserved in April 2025 and published in December 2025, indicating recent discovery. Given the critical role of FL SWITCH 2005 in industrial control systems, this vulnerability poses a risk to operational continuity if exploited.

For European organizations, especially those in industrial automation, manufacturing, energy, and critical infrastructure sectors, this vulnerability can lead to denial-of-service conditions on network switches that are integral to operational technology (OT) environments. Disruption of the FL SWITCH 2005 webserver can impair remote management, monitoring, and control capabilities, potentially causing downtime or degraded performance in industrial processes. This can have cascading effects on production lines, safety systems, and supply chains. Since the vulnerability does not affect confidentiality or integrity, data breaches are unlikely; however, availability impacts can result in significant operational and financial losses. The ease of exploitation due to low privilege requirements and no need for user interaction increases the risk profile, especially in environments where these devices are accessible from less trusted networks. European organizations relying on Phoenix Contact products must consider this vulnerability a threat to their industrial network resilience.

Given the absence of an official patch, European organizations should implement immediate compensating controls. First, restrict access to the FL SWITCH 2005 webshell interface by network segmentation and firewall rules, limiting exposure to trusted management networks only. Employ strict access control lists (ACLs) to prevent unauthorized remote access. Monitor network traffic for anomalous patterns indicative of repeated empty or whitespace command attempts that could signal exploitation attempts. Implement rate limiting or connection throttling at network perimeter devices to mitigate resource exhaustion attempts. Regularly audit device configurations to ensure minimal exposure of management interfaces. Engage with Phoenix Contact support channels to obtain updates on patch availability and apply them promptly once released. Additionally, consider deploying intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts targeting this vulnerability. Document and rehearse incident response plans to quickly address potential DoS events affecting critical network infrastructure.