CVE-2025-9999: Network Station RCE Vulnerability

CVE-2025-9999 Overview

CVE-2025-9999 is a high severity vulnerability affecting the inter-station messaging architecture of PCVue, a SCADA and HMI platform. Some payload elements exchanged between two stations are not properly validated on the receiving station. An attacker positioned on the adjacent network can craft malicious messages to execute unauthorized commands inside the application. The weakness is classified under CWE-940 (Improper Verification of Source of a Communication Channel). The vulnerability is documented in the PCVue Security Bulletin SB2025-4.

Critical Impact
An adjacent-network attacker can inject crafted message payloads between PCVue stations to execute unauthorized application commands, threatening the confidentiality and integrity of supervisory control workflows.

Affected Products

PCVue (inter-station networking component)
Refer to PCVue Security Bulletin SB2025-4 for affected version ranges
Deployments using multi-station PCVue architectures

Discovery Timeline

2025-09-05 - CVE-2025-9999 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-9999

Vulnerability Analysis

PCVue supports distributed deployments in which multiple stations exchange operational messages over a network. The receiving station processes payload elements from peer stations without applying sufficient validation. An attacker who can place traffic on the same logical network segment can deliver malicious payloads that the receiving station interprets as legitimate application input. The result is execution of unauthorized commands within the PCVue application context, which can manipulate supervisory data flows and operator-facing functions. Successful exploitation requires network adjacency and the ability to interact with the inter-station protocol, but does not require authentication or user interaction on the target. The flaw maps to CWE-940, reflecting a failure to verify the trustworthiness of the communication source and content.

Root Cause

The root cause is missing or insufficient validation of payload fields contained in inter-station messages. The receiving station trusts the structure and semantics of incoming data without enforcing source authentication or strict input checks. This allows an attacker to embed unauthorized command directives in fields that the application later processes as control instructions.

Attack Vector

The attack vector is adjacent network. An attacker must reach the inter-station communication channel between two PCVue stations. Once positioned, the attacker sends a crafted message containing manipulated payload elements. The receiving station processes the payload and executes commands within the application. No prior credentials and no operator interaction are needed to trigger the condition.

No public proof-of-concept code has been verified for this CVE. Refer to the PCVue Security Bulletin SB2025-4 for vendor-supplied technical details.

Detection Methods for CVE-2025-9999

Indicators of Compromise

Unexpected inter-station messages originating from hosts that are not authorized PCVue stations
Application-level command executions in PCVue logs without a corresponding operator action
Anomalous payload sizes or field values in PCVue station-to-station traffic

Detection Strategies

Capture and inspect PCVue inter-station network traffic for malformed or oversized payload fields
Baseline normal message structure between stations and alert on deviations
Correlate PCVue application command events with authenticated operator sessions to identify orphaned commands

Monitoring Recommendations

Forward PCVue application and station logs to a centralized SIEM for retention and correlation
Monitor switch and firewall logs for unexpected hosts communicating on the PCVue station VLAN
Alert on new MAC or IP addresses appearing on segments dedicated to supervisory control traffic

How to Mitigate CVE-2025-9999

Immediate Actions Required

Review the PCVue Security Bulletin SB2025-4 and apply the vendor-supplied update for affected versions
Restrict the network segment carrying PCVue inter-station messages to authorized stations only
Audit firewall and switch ACLs to confirm no unauthorized hosts can reach the inter-station protocol ports

Patch Information

Arc Informatique has published remediation guidance in PCVue Security Bulletin SB2025-4. Operators should consult the bulletin for the fixed version numbers and upgrade procedures applicable to their deployment.

Workarounds

Place PCVue stations on a dedicated, isolated VLAN with strict ingress and egress filtering
Enforce network access control so only known station endpoints can join the supervisory segment
Use encrypted and authenticated transport between stations where supported by the platform
Monitor inter-station traffic with an industrial protocol-aware intrusion detection system