CVE-2026-61892 Overview
CVE-2026-61892 is a privilege escalation vulnerability affecting the Weintek cMT3092X Human-Machine Interface (HMI). A non-privileged authenticated user can modify session tokens to elevate their privileges on the device. The flaw is categorized under [CWE-732] (Incorrect Permission Assignment for Critical Resource) and impacts operational technology (OT) environments where HMIs bridge industrial control systems and operator workstations.
The vulnerability was published to the National Vulnerability Database on 2026-07-24 and last modified on 2026-07-30. CISA published advisory ICSA-26-204-03 covering the issue.
Critical Impact
An authenticated low-privileged user can tamper with tokens to gain elevated privileges on the HMI, exposing industrial process control to unauthorized modification.
Affected Products
- Weintek cMT3092X HMI
- cMT EasyWeb V2 (per vendor security document)
- Additional cMT series products may be affected — consult the vendor advisory
Discovery Timeline
- 2026-07-24 - CVE-2026-61892 published to NVD
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-61892
Vulnerability Analysis
The Weintek cMT3092X HMI issues authentication tokens to clients after login. The device does not adequately validate or bind token contents to the issuing principal. A non-privileged operator authenticated to the HMI web interface can modify token fields — for example, role or privilege claims — and resubmit the token to obtain administrator-level access.
Once elevated, an attacker can alter HMI project configurations, manipulate process values, disable monitoring, or pivot to connected programmable logic controllers (PLCs). In industrial deployments, such actions can disrupt production, damage equipment, or create safety hazards. The vulnerability is reachable over the network from any account with legitimate low-privileged access.
Root Cause
The root cause is an incorrect permission assignment on the token validation path [CWE-732]. The HMI trusts client-supplied token content for authorization decisions instead of verifying integrity against a server-side secret or cryptographic signature. This design permits arbitrary claim tampering by any authenticated user.
Attack Vector
The attack requires network access to the HMI and valid low-privileged credentials. The attacker authenticates, captures an issued token, modifies claims that determine privilege level, and replays the modified token against protected endpoints. No user interaction is required beyond the attacker's own session. Because HMIs are frequently exposed to plant networks and occasionally reachable from IT segments, the effective attack surface is broad.
No public proof-of-concept exploit is available at time of writing. The EPSS score is 0.274% with a percentile of 19.6, but OT exposure warrants prompt remediation regardless of statistical exploit likelihood.
Refer to the Weintek Security Issues Document and CISA ICS Advisory ICSA-26-204-03 for vendor-supplied technical details.
Detection Methods for CVE-2026-61892
Indicators of Compromise
- Unexpected administrator actions in HMI audit logs originating from accounts provisioned as operators or viewers
- Token values in HTTP requests that fail server-side integrity checks or contain modified privilege claims
- Configuration changes to HMI projects, tag mappings, or PLC connections outside authorized change windows
Detection Strategies
- Enable HMI audit logging and forward events to a centralized SIEM for correlation across sessions and users
- Alert on privilege escalations where an account performs administrative actions without a preceding role change
- Inspect north-south and east-west traffic to HMIs for repeated token submissions from a single source with varying claim values
Monitoring Recommendations
- Baseline normal HMI user roles and flag deviations in real time
- Monitor for authentication anomalies such as repeated failed authorization attempts followed by successful privileged access
- Track configuration diffs on cMT3092X devices and integrate change alerts with OT incident response workflows
How to Mitigate CVE-2026-61892
Immediate Actions Required
- Apply the firmware update referenced in the Weintek security document as soon as it is available for your model
- Restrict network access to the cMT3092X HMI to authorized engineering workstations using firewall rules and VLAN segmentation
- Audit all HMI user accounts and remove unused or shared low-privileged accounts that could be abused for token manipulation
- Rotate all HMI credentials and, where supported, revoke existing sessions after patching
Patch Information
Weintek has published guidance in TEC25003E_cMT_EasyWeb_V2_Security_Issues. Consult the vendor for the specific firmware version that remediates CVE-2026-61892 on the cMT3092X model. CISA advisory ICSA-26-204-03 provides additional remediation guidance for asset owners.
Workarounds
- Place the HMI behind a jump host or VPN and prohibit direct access from general-purpose corporate networks
- Enforce least privilege on HMI accounts and disable web-based administration where operationally feasible
- Deploy network monitoring on OT segments to detect anomalous authentication traffic to cMT devices
# Example firewall restriction (adapt to your platform)
# Allow only engineering subnet to reach the HMI web interface
iptables -A FORWARD -s 10.20.30.0/24 -d <HMI_IP> -p tcp --dport 443 -j ACCEPT
iptables -A FORWARD -d <HMI_IP> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
