CVE-2026-82789: CONPROSYS HMI System Eval Injection RCE Flaw

CVE-2026-82789 Overview

CVE-2026-82789 is an eval injection vulnerability [CWE-95] affecting the CONPROSYS HMI System (CHS) developed by Contec. The flaw stems from improper neutralization of directives passed to a dynamic code evaluation routine. An authenticated attacker with the ability to log in to the product can inject crafted input that the application evaluates as executable code, resulting in arbitrary code execution in the context of the CHS process.

Critical Impact
Authenticated attackers can execute arbitrary code on affected CONPROSYS HMI Systems, compromising the confidentiality, integrity, and availability of industrial human-machine interface deployments.

Affected Products

Contec CONPROSYS HMI System (CHS)
Refer to the Contec Security Information Document for exact affected versions
Refer to the JVN Security Vulnerability Report for coordinated disclosure details

Discovery Timeline

2026-09-14 - CVE-2026-82789 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-82789

Vulnerability Analysis

CONPROSYS HMI System (CHS) is a browser-based human-machine interface platform used in industrial control environments. The vulnerability is classified as Improper Neutralization of Directives in Dynamically Evaluated Code [CWE-95], commonly known as eval injection. User-supplied input reaches a dynamic evaluation function without adequate sanitization or allow-listing. When the application evaluates the crafted payload, the attacker's directives execute as native code within the CHS runtime.

Successful exploitation grants the attacker the privileges of the CHS process. In industrial deployments this can translate into manipulation of monitoring dashboards, unauthorized changes to control logic references, or a pivot into adjacent operational technology networks. Because CHS often bridges IT and OT segments, code execution here materially expands the blast radius of a compromise.

Root Cause

The root cause is the use of a dynamic code evaluation primitive on data influenced by an authenticated user. The application lacks a strict input filter or safe expression parser, so metacharacters and language constructs pass unmodified into the evaluator.

Attack Vector

The attack vector is network-based and requires low privileges. An attacker who has valid credentials or who has obtained session access through credential theft, brute force, or reuse can submit the malicious payload through the application interface. No user interaction is required. Refer to the vendor and JVN advisories for the specific request paths and parameters that trigger the flaw.

Detection Methods for CVE-2026-82789

Indicators of Compromise

Unexpected child processes spawned by the CHS application service on the HMI host.
Application or web server logs containing script metacharacters, language keywords, or serialized expressions in parameters submitted by authenticated users.
Outbound network connections from the CHS host to unfamiliar destinations shortly after authenticated sessions.
New or modified files in the CHS installation or web root without a corresponding change ticket.

Detection Strategies

Correlate authenticated CHS sessions with process creation telemetry on the host to surface anomalous execution chains.
Alert on requests to CHS endpoints containing evaluator syntax such as function calls, backticks, or template delimiters.
Baseline normal CHS process behavior and flag deviations, including unexpected command interpreters or scripting engines being launched.

Monitoring Recommendations

Forward CHS application, authentication, and host process logs to a centralized analytics platform for retention and correlation.
Monitor login activity for CHS accounts and alert on logins from new source addresses or outside operational hours.
Track file integrity on CHS binaries, configuration files, and web assets.

How to Mitigate CVE-2026-82789

Immediate Actions Required

Apply the fixed version published by Contec as described in the vendor advisory as soon as it can be validated in your environment.
Restrict network reachability of the CHS management interface to trusted engineering workstations and jump hosts only.
Rotate CHS account credentials and enforce strong, unique passwords for every operator and administrator.
Audit existing CHS accounts and remove any that are no longer required.

Patch Information

Contec has published guidance and fixed versions in the Contec Security Information Document. Additional coordinated disclosure information is available in the JVN Security Vulnerability Report. Administrators should consult these advisories for the exact patched build and upgrade procedure.

Workarounds

Place the CHS server behind a firewall or VPN so that only authenticated operators on trusted network segments can reach the interface.
Segment the CHS host from general IT networks and from any internet-facing infrastructure following ISA/IEC 62443 zone and conduit guidance.
Enable multi-factor authentication in front of the CHS interface where the deployment architecture supports it, for example via a reverse proxy.
Continuously monitor CHS authentication and process activity until the vendor patch is deployed.

bash

# Example: restrict inbound access to the CHS web interface to a trusted engineering subnet
# Adjust the interface, port, and CIDR to match the local environment
iptables -A INPUT -p tcp --dport 8000 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8000 -j DROP