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How CVE-2026-1692 Works
This vulnerability stems from a missing origin validation in WebSockets, specifically affecting the GraphicalData web services of PcVue versions 12.0.0 through 16.3.3. WebSockets, unlike traditional HTTP requests, are not automatically bound by the Same-Origin Policy, requiring explicit server-side validation of the Origin header during the handshake process. The PcVue implementation fails to perform this critical validation on two specific SignalR endpoints: GraphicalData/js/signalR/connect and GraphicalData/js/signalR/reconnect. This oversight allows a malicious website to establish a full-duplex WebSocket connection to a victim’s PcVue instance if the victim is currently authenticated. An attacker can host a crafted webpage containing JavaScript that initiates WebSocket connections to these vulnerable endpoints. When a successfully authenticated PcVue user visits this malicious site, the browser sends the user’s existing session cookies along with the WebSocket handshake request. Since the server does not verify the Origin header, it accepts the connection as legitimate, effectively granting the attacker the ability to interact with the PcVue web services using the victim’s authenticated session. The attack vector is network-based and requires user interaction—specifically, luring an authenticated user to a malicious website. The impact is limited to confidentiality and integrity loss at both the vulnerability and subsequent system scope levels, with no availability impact. The vulnerability is classified under CWE-1385 (Missing Origin Validation in WebSockets) and affects the WebVue, WebScheduler, TouchVue, and SnapVue features. No public proof-of-concept or active exploitation has been reported as of publication, but the risk remains significant for industrial control system environments where PcVue is deployed for monitoring and visualization.
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Platform: PcVue
Version: 12.0.0 through 16.3.3
Vulnerability: Missing Origin Validation
Severity: Medium
Date: February 26, 2026
Prediction: April 2026
What Undercode Say:
Bash Commands and Code Examples
Example nginx reverse proxy configuration to validate Origin headers
Add to server block handling PcVue web services
map $http_origin $allowed_origin {
default "";
"~^https://trusted-pcvue-domain\.com$" $http_origin;
"~^https://subdomain\.trusted-domain\.com$" $http_origin;
}
location /GraphicalData/js/signalR/ {
Block requests with missing or disallowed origins
if ($allowed_origin = "") {
return 403;
}
Pass validated origin to backend
proxy_set_header Origin $allowed_origin;
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;
}
Check for vulnerable endpoints in logs
grep -E "GraphicalData/js/signalR/(connect|reconnect)" /var/log/pcvue/access.log | awk '{print $1, $4, $7, $11}' | column -t
Test for origin validation (requires authenticated session)
curl -H "Origin: https://malicious-site.com" \
-H "Cookie: SESSIONID=valid_session_cookie" \
-H "Upgrade: websocket" \
-H "Connection: Upgrade" \
http://target-pcvue/GraphicalData/js/signalR/connect
Monitor WebSocket connections with tcpdump
tcpdump -i any -A -s 0 'tcp port 80 and (tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420 or tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x504f5354)' | grep -E "Origin:|WebSocket|signalR"
How Exploit
Attack Chain: Attacker hosts malicious website → Lures authenticated PcVue user → User’s browser connects to vulnerable endpoints → WebSocket hijacked
Technique: Cross-Site WebSocket Hijacking (CSWSH) leveraging missing Origin validation
Requirements: Valid authenticated session in target PcVue instance; User interaction (visiting malicious site)
Vulnerable Endpoints: GraphicalData/js/signalR/connect and GraphicalData/js/signalR/reconnect
Exploit Code Concept (JavaScript on attacker site):
var ws = new WebSocket("ws://target-pcvue/GraphicalData/js/signalR/connect");
ws.onopen = function() { ws.send("malicious payload"); };
Impact Actions: Intercept real-time data streams; Send unauthorized commands; Access sensitive graphical data; Perform operations within victim’s session context
Protection from this CVE
Immediate Patching: Upgrade to PcVue version beyond 16.3.3 when vendor patch releases (refer to SB2026-2)
Network Segmentation: Isolate PcVue web services behind firewalls; Restrict access to trusted networks only
Reverse Proxy Validation: Implement origin header validation at proxy level (see nginx example above)
Web Application Firewall: Deploy WAF rules to inspect WebSocket handshakes and block unexpected origins
Content Security Policy: Add CSP headers restricting WebSocket connections to same-origin only
Disable Unused Features: Uninstall or disable WebVue, WebScheduler, TouchVue, SnapVue if not required
User Education: Train users to avoid suspicious links while authenticated to PcVue services
Monitoring: Enable verbose logging for SignalR endpoints; Alert on connections from unusual origin headers
Impact
Confidentiality Breach: Potential exposure of real-time industrial data streams, graphical visualizations, and sensitive SCADA information
Integrity Compromise: Attackers may send unauthorized commands or manipulate data within authenticated sessions
Affected Components: WebVue, WebScheduler, TouchVue, SnapVue features across versions 12.0.0 through 16.3.3
Attack Scope: Requires authenticated user interaction but no additional privileges once exploited
CVSS Score: 5.3 MEDIUM (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/AU:Y/R:U/RE:M/U:Clear)
Risk Context: Critical for industrial control system (ICS) and SCADA environments where PcVue monitors infrastructure
Business Impact: Unauthorized data access; Potential operational disruption; Regulatory compliance violations
Current Status: No known active exploitation; No public PoC available; Vendor advisory published
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Sources:
Reported By: nvd.nist.gov
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