CVE-2026-1692: PcVue WebSockets CSRF Vulnerability

CVE-2026-1692 Overview

A missing origin validation in WebSockets vulnerability affects the GraphicalData web services used by the WebVue, WebScheduler, TouchVue and SnapVue features of PcVue. This vulnerability exists in versions 12.0.0 through 16.3.3 and could allow a remote attacker to lure a successfully authenticated user to a malicious website, potentially leading to unauthorized actions on behalf of the victim.

The vulnerability specifically impacts two SignalR endpoints: GraphicalData/js/signalR/connect and GraphicalData/js/signalR/reconnect. The lack of proper origin validation in these WebSocket connections creates an opportunity for cross-site WebSocket hijacking attacks.

Critical Impact

Authenticated users of PcVue web services may be susceptible to cross-site WebSocket hijacking attacks, potentially allowing attackers to perform unauthorized actions or access sensitive data through malicious websites.

Affected Products

• PcVue versions 12.0.0 through 16.3.3
• WebVue feature component
• WebScheduler feature component
• TouchVue feature component
• SnapVue feature component

Discovery Timeline

• 2026-02-26 - CVE CVE-2026-1692 published to NVD
• 2026-02-26 - Last updated in NVD database

Technical Details for CVE-2026-1692

Vulnerability Analysis

This vulnerability stems from CWE-1385 (Missing Origin Validation in WebSockets), a security weakness where WebSocket connections fail to properly validate the origin of incoming requests. In the context of PcVue's GraphicalData web services, the SignalR endpoints do not adequately verify that WebSocket connection requests originate from trusted sources.

WebSockets, unlike traditional HTTP requests, are not bound by the same-origin policy by default. This means that without explicit origin validation, a malicious website can establish WebSocket connections to vulnerable endpoints if a user has an active authenticated session. The vulnerability affects industrial control system (ICS) monitoring and SCADA visualization components, which are critical infrastructure elements requiring strong security controls.

Root Cause

The root cause of this vulnerability is the absence of origin header validation in the WebSocket handshake process for the GraphicalData SignalR endpoints. When a WebSocket connection is initiated, the server does not verify that the Origin header matches the expected domain(s). This allows cross-origin WebSocket connections from any domain, including attacker-controlled websites.

SignalR, the underlying real-time communication framework, relies on the application layer to implement proper origin checks. Without this validation, the framework accepts connections regardless of their source, enabling potential cross-site WebSocket hijacking (CSWSH) attacks.

Attack Vector

The attack vector for this vulnerability is network-based and requires user interaction. An attacker would need to:

1. Set up a malicious website containing JavaScript code designed to establish WebSocket connections to the vulnerable PcVue endpoints
2. Lure an authenticated PcVue user to visit the malicious website
3. Exploit the victim's active session to establish a WebSocket connection to the SignalR endpoints
4. Intercept real-time data streams or send malicious commands through the hijacked connection

The vulnerability manifests in the WebSocket connection handshake at the GraphicalData/js/signalR/connect and GraphicalData/js/signalR/reconnect endpoints. Without proper origin validation, the server cannot distinguish between legitimate requests from the PcVue application and malicious requests from attacker-controlled domains. See the PCVue Security Bulletin SB2026-2 for additional technical details.

Detection Methods for CVE-2026-1692

Indicators of Compromise

• Unexpected WebSocket connections to SignalR endpoints from unusual origin headers
• Connection attempts to GraphicalData/js/signalR/connect or GraphicalData/js/signalR/reconnect with external referrer domains
• Anomalous patterns in SignalR connection logs showing connections from unfamiliar client IP addresses during user sessions

Detection Strategies

• Implement logging and alerting for WebSocket connections with origin headers that do not match expected PcVue domains
• Monitor web server access logs for requests to the affected SignalR endpoints with suspicious referrer headers
• Deploy network intrusion detection rules to identify cross-origin WebSocket connection attempts
• Analyze user session activity for concurrent connections from disparate geographic locations

Monitoring Recommendations

• Enable verbose logging for SignalR connections in PcVue web services
• Configure web application firewalls (WAF) to log and alert on WebSocket connections with mismatched origins
• Implement user behavior analytics to detect session anomalies that may indicate hijacked connections
• Monitor for phishing campaigns targeting PcVue users that may be attempting to exploit this vulnerability

How to Mitigate CVE-2026-1692

Immediate Actions Required

• Upgrade PcVue installations to a patched version that addresses the missing origin validation (check vendor security bulletin for specific version recommendations)
• Review and restrict network access to the GraphicalData web services to trusted networks only
• Implement web application firewall rules to validate WebSocket origin headers
• Educate users about phishing risks and avoiding suspicious links while logged into PcVue services

Patch Information

ARC Informatique has released security information regarding this vulnerability. Organizations should consult the PCVue Security Bulletin SB2026-2 for specific patch versions and upgrade instructions. Apply the recommended patches to all affected PcVue installations as soon as possible.

Workarounds

• Configure reverse proxy or load balancer to enforce origin validation for WebSocket connections before they reach PcVue services
• Implement network segmentation to limit access to PcVue web services from untrusted networks
• Deploy Content Security Policy (CSP) headers on PcVue web applications to restrict WebSocket connections to same-origin only
• Consider disabling the affected web features (WebVue, WebScheduler, TouchVue, SnapVue) if they are not critical to operations until patches can be applied

# Example nginx configuration for origin validation
# Add to server block handling PcVue web services
map $http_origin $cors_origin {
    default "";
    "~^https://trusted-pcvue-domain\.com$" $http_origin;
}

location /GraphicalData/js/signalR/ {
    if ($cors_origin = "") {
        return 403;
    }
    proxy_pass http://pcvue_backend;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $host;
    proxy_set_header Origin $cors_origin;
}