CVE-2025-9998 is a medium-severity vulnerability affecting arcinfo's PcVue software versions 12.0, 15.0, and 16.0. The vulnerability stems from improper handling of the sequence of packets received by the networking server component of PcVue. Specifically, the application fails to correctly check for unusual or exceptional conditions in the incoming network messages, classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions). An attacker can exploit this flaw by sending specially crafted network packets that disrupt the normal processing logic, causing the application to stop or crash. The vulnerability does not require user interaction or authentication, but it has a high attack complexity, meaning exploitation requires specific conditions or knowledge. The CVSS 4.0 vector indicates the attack is network-based (AV:A), with high complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), and no impact on confidentiality, integrity, or availability directly, but with a high impact on availability (VA:H). The vulnerability is not known to be exploited in the wild yet, and no patches have been published at the time of disclosure. PcVue is a supervisory control and data acquisition (SCADA) and industrial automation software widely used in critical infrastructure and industrial environments for monitoring and controlling processes. The improper packet validation could lead to denial of service conditions, potentially disrupting industrial operations relying on PcVue for real-time control and monitoring.

For European organizations, particularly those in critical infrastructure sectors such as energy, manufacturing, transportation, and utilities that rely on PcVue for industrial control systems (ICS), this vulnerability poses a risk of operational disruption. An attacker exploiting this flaw could cause denial of service by forcing the PcVue application to stop, interrupting monitoring and control processes. This could lead to safety risks, production downtime, and financial losses. Given the high attack complexity, exploitation may be limited to skilled adversaries with network access to the PcVue server. However, the lack of required authentication and user interaction increases the risk if network segmentation and access controls are weak. The impact is primarily on availability, which is critical in industrial environments where continuous operation is essential. Disruption could also indirectly affect data integrity and safety if control commands are delayed or lost. The absence of known exploits in the wild currently reduces immediate risk, but the vulnerability's presence in multiple versions suggests a broad attack surface in European industrial environments.

European organizations using PcVue should implement the following specific mitigations: 1) Immediately assess and inventory all PcVue installations, identifying affected versions (12.0, 15.0, 16.0). 2) Apply vendor patches or updates as soon as they become available; if no patches exist yet, engage with arcinfo support for guidance or workarounds. 3) Strengthen network segmentation to isolate PcVue servers from untrusted networks, limiting exposure to potential attackers. 4) Implement strict firewall rules and intrusion detection/prevention systems (IDS/IPS) to monitor and block anomalous or malformed packets targeting PcVue networking ports. 5) Conduct network traffic analysis to detect unusual packet sequences or patterns that could indicate exploitation attempts. 6) Employ redundancy and failover mechanisms for PcVue servers to minimize operational impact in case of service disruption. 7) Train operational technology (OT) security teams on this vulnerability and incident response procedures specific to industrial control systems. 8) Regularly review and update access controls to ensure only authorized personnel and systems can communicate with PcVue servers. These targeted measures go beyond generic advice by focusing on network-level protections, monitoring, and operational continuity specific to PcVue environments.