CVE-2026-61886: Weintek cMT3092X HMI Plaintext Password

CVE-2026-61886 Overview

CVE-2026-61886 is a plaintext credential storage flaw in the Weintek cMT3092X Human-Machine Interface (HMI). The device stores user account passwords without encryption or hashing, mapping to [CWE-256] Plaintext Storage of a Password. An authenticated attacker with low privileges can access stored credentials over the network and reuse them to escalate access on the operational technology (OT) network.

The issue affects industrial control system (ICS) environments where HMIs mediate operator access to programmable logic controllers (PLCs) and process equipment. CISA published advisory ICSA-26-204-03 documenting the flaw and coordinated remediation with Weintek.

Critical Impact
Attackers with network access and valid low-privilege credentials can retrieve plaintext passwords stored on the HMI and pivot to other operator or administrator accounts on the industrial network.

Affected Products

Weintek cMT3092X HMI
Weintek cMT series devices running affected EasyWeb V2 firmware (per vendor advisory)
Industrial control system deployments integrating the cMT3092X HMI

Discovery Timeline

2026-07-24 - CVE-2026-61886 published to the National Vulnerability Database (NVD)
2026-07-30 - Last updated in NVD database

Technical Details for CVE-2026-61886

Vulnerability Analysis

The Weintek cMT3092X HMI stores local user account passwords as plaintext on the device. When an authenticated user queries account data or accesses the underlying storage location, the credentials are returned or read in cleartext. This eliminates the confidentiality guarantee normally provided by one-way hashing or encryption at rest.

Because HMIs are often shared across operators and engineers, a single low-privileged foothold can expose credentials belonging to higher-privileged accounts. Reused passwords across engineering workstations, SCADA servers, and PLCs extend the blast radius beyond the HMI itself.

The attack requires network reachability to the HMI and valid low-privilege credentials. No user interaction is needed. The confidentiality impact is high while integrity and availability of the HMI remain unaffected by this specific weakness.

Root Cause

The root cause is the HMI's credential storage design. Account passwords are persisted in a recoverable form rather than as salted cryptographic hashes. This violates the [CWE-256] guidance that authentication secrets must never be recoverable from storage.

Attack Vector

An attacker authenticates to the HMI with a low-privilege account over the network. The attacker then reads the stored credential material through supported interfaces or configuration exports. Recovered passwords are reused against administrator accounts on the same HMI or against adjacent OT assets that share credentials. The vulnerability is described in prose only; no verified public exploit code is available at the time of writing. See the Weintek Security Issues Document for vendor technical detail.

Detection Methods for CVE-2026-61886

Indicators of Compromise

Unexpected authentication events on the cMT3092X HMI from operator subnets or engineering workstations outside normal shift patterns.
Configuration export or backup requests issued by low-privilege HMI accounts.
Reuse of HMI account passwords observed on adjacent PLCs, SCADA servers, or jump hosts.

Detection Strategies

Monitor HMI web and management interface logs for successful logins followed by configuration read or export operations.
Alert on lateral authentication from HMI-adjacent hosts to engineering assets using accounts scoped only to the HMI.
Baseline expected operator activity on the HMI and flag deviations in session source, time, or command sequence.

Monitoring Recommendations

Forward HMI access logs and OT network flow data to a centralized SIEM or data lake for correlation with IT telemetry.
Deploy passive OT network monitoring to detect unusual traffic between the HMI and non-operator endpoints.
Track credential reuse across OT and IT boundaries using identity analytics tied to shared account inventories.

How to Mitigate CVE-2026-61886

Immediate Actions Required

Apply the firmware update referenced in the CISA ICS Advisory ICSA-26-204-03 as soon as the vendor patch is validated for your environment.
Rotate every HMI account password and change any credentials reused on adjacent OT or IT systems.
Restrict network access to the HMI to a dedicated engineering VLAN with explicit allowlists.

Patch Information

Refer to the Weintek Security Issues Document for the vendor-supplied firmware update and configuration guidance addressing plaintext credential storage. Coordinate deployment with the CISA ICS Advisory and the CSAF advisory record.

Workarounds

Place the HMI behind a firewall and block all inbound access except from authorized engineering workstations.
Disable unused local accounts on the HMI and enforce unique, strong passwords per account.
Segment the OT network so that HMI compromise does not grant direct access to PLCs, historians, or corporate assets.
Use jump hosts with multi-factor authentication for any administrative session to the HMI.

bash

# Example firewall restriction (adapt to your environment)
# Allow only the engineering workstation subnet to reach the HMI management port
iptables -A FORWARD -s 10.20.30.0/24 -d 10.10.10.15 -p tcp --dport 443 -j ACCEPT
iptables -A FORWARD -d 10.10.10.15 -j DROP