CVE-2026-10825 Overview
CVE-2026-10825 is a denial-of-service vulnerability affecting the WebSocket API of Moxa serial device servers. The flaw stems from improper validation and handling of JSON-based requests sent to the management interface. A low-privileged authenticated attacker can transmit a specially crafted request that disrupts service operation and can trigger an unexpected device reboot. The issue is tracked under CWE-1287: Improper Validation of Specified Type of Input and is documented in Moxa Security Advisory MPSA-268270.
Critical Impact
An authenticated low-privileged attacker on the network can force a Moxa serial device server to reboot, interrupting industrial serial-to-Ethernet communications.
Affected Products
- Moxa serial device servers exposing the WebSocket management API
- Refer to Moxa Security Advisory MPSA-268270 for the full list of impacted models and firmware versions
Discovery Timeline
- 2026-06-16 - CVE-2026-10825 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-10825
Vulnerability Analysis
The vulnerability resides in the WebSocket API exposed by affected Moxa serial device servers. The API accepts JSON-encoded requests for device configuration and runtime operations. The handler fails to enforce strict type, structure, and value validation on incoming JSON payloads. As a result, malformed or unexpected JSON content propagates into downstream processing logic where it triggers unrecoverable error states.
When the unhandled input reaches a sensitive code path, the device firmware fails ungracefully. The impact ranges from temporary service interruption to a full system reboot. Because serial device servers bridge industrial serial endpoints to TCP/IP networks, a reboot severs every active session traversing the device. Operators using these devices for OT, SCADA, or remote console access lose connectivity until the device finishes its restart cycle.
Root Cause
The root cause is improper validation of a specified type of input [CWE-1287]. The WebSocket request parser does not verify that JSON fields conform to expected schemas, data types, or value ranges before dispatching them to internal subsystems. Invalid input bypasses checks and reaches code that cannot safely process it.
Attack Vector
Exploitation requires network access to the WebSocket API and valid low-privileged credentials. No user interaction is required. An attacker authenticates to the device, opens a WebSocket session, and submits a crafted JSON message. The malformed payload disrupts the service and may force the device to reboot. Technical specifics of the offending request structure are not published by the vendor.
No public proof-of-concept is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2026-10825
Indicators of Compromise
- Unexpected reboot events or watchdog-triggered restarts logged by Moxa serial device servers
- Abrupt termination of WebSocket sessions originating from low-privileged accounts
- Loss of serial-to-Ethernet tunnels coinciding with anomalous JSON traffic to the management interface
- Repeated authentication followed by short-lived WebSocket sessions from a single source
Detection Strategies
- Inspect WebSocket traffic to the device management interface for malformed or oversized JSON payloads
- Correlate device reboot syslog events with preceding authenticated WebSocket activity
- Alert on low-privileged accounts initiating administrative WebSocket sessions outside normal change windows
- Baseline normal JSON request structures and flag deviations in field types or nesting depth
Monitoring Recommendations
- Forward syslog and SNMP traps from Moxa devices to a centralized log platform for reboot and crash tracking
- Monitor availability of serial tunnels using continuous probes and alert on session loss
- Track authentication patterns on the device management plane and flag credential reuse from unexpected sources
- Capture packet metadata on segments hosting serial device servers for retrospective analysis
How to Mitigate CVE-2026-10825
Immediate Actions Required
- Apply firmware updates as published in Moxa Security Advisory MPSA-268270
- Restrict network access to the WebSocket management interface to a dedicated management VLAN
- Rotate credentials on all low-privileged accounts with access to affected devices
- Audit existing accounts and remove unused or shared management identities
Patch Information
Moxa has published remediation guidance in advisory MPSA-268270. Administrators must consult the advisory for the specific firmware versions that address CVE-2026-10825 and follow Moxa's documented upgrade procedure for each impacted product line.
Workarounds
- Place affected devices behind a firewall that permits management traffic only from trusted administrative hosts
- Disable the WebSocket API on devices where it is not operationally required
- Enforce least privilege by removing management access from accounts that do not need it
- Implement network access control lists to block untrusted sources from reaching device management ports
# Example firewall ACL restricting WebSocket management access to a trusted subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -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.
