CVE-2025-2026 is a vulnerability classified under CWE-170 (Improper Null Termination) affecting Moxa NPort 6100-G2 and 6200-G2 Series devices, specifically version 1.0.0. The flaw resides in the device’s web API, where improper handling of null bytes allows an authenticated remote attacker with read-only web privileges to inject null byte characters into API requests. This injection leads to unexpected device behavior, specifically causing the device to reboot. The reboot disrupts normal operations, resulting in a denial-of-service condition. The vulnerability does not require user interaction and can be exploited remotely over the network, with low attack complexity and no need for elevated privileges beyond read-only web access. The CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N) reflects a network attack vector, low complexity, no user interaction, and high impact on availability. Although no public exploits are currently known, the vulnerability could be leveraged to disrupt industrial or network communication infrastructure where these devices are deployed. The lack of patches at the time of publication necessitates proactive mitigation strategies.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Moxa NPort 6100-G2/6200-G2 Series devices in critical infrastructure, industrial automation, or network management. The forced reboot caused by exploitation leads to denial of service, potentially interrupting communication between serial devices and networked systems. This can affect manufacturing processes, SCADA systems, or other operational technology environments, causing downtime and operational delays. The disruption could also impact service availability and safety monitoring systems, increasing risk exposure. Since the vulnerability requires only read-only web access, insider threats or compromised credentials could be sufficient to exploit it. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time. Organizations in sectors such as energy, transportation, and manufacturing across Europe should be particularly vigilant.

1. Restrict access to the web API of Moxa NPort 6100-G2/6200-G2 devices to trusted networks and users only, employing network segmentation and firewall rules. 2. Enforce strong authentication and credential management to prevent unauthorized access, even at read-only privilege levels. 3. Monitor device logs and network traffic for unusual API requests or unexpected reboots that may indicate exploitation attempts. 4. Engage with Moxa for timely updates or patches addressing this vulnerability; apply patches immediately once available. 5. Consider deploying intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous API activity targeting these devices. 6. Implement redundancy and failover mechanisms in critical systems to minimize operational impact if a device reboots unexpectedly. 7. Conduct regular security assessments and penetration testing focusing on industrial control and network devices to identify similar vulnerabilities.