CVE-2019-6829:

CVE-2019-6829: CWE-248 Uncaught Exception vulnerability in Schneider Electric Modicon M580 and M340 controllers, which could lead to denial of service when writing to specific memory addresses over Modbus. Affected firmware versions: M580 prior to V2.90 and M340 prior to V3.10.

Score
A numerical rating that indicates how dangerous this vulnerability is.

7.5High

Published Date:Sep 17, 2019
CISA KEV Date:*No Data*
Industries Affected:20

Threat Predictions

EPSS Score:0.4
EPSS Percentile:58%

Exploitability

Score:3.9
Attack Vector:NETWORK
Attack Complexity:LOW
Privileges Required:NONE
User Interaction:NONE
Scope:UNCHANGED

Impact

Score:3.6
Confidentiality Impact:NONE
Integrity Impact:NONE
Availability Impact:HIGH

Description Preview

Overview

An uncaught exception (CWE-248) can be triggered during Modbus write operations to specific memory addresses on affected Schneider Electric Modicon devices, potentially causing denial of service. The issue affects firmware versions prior to 2.90 on the M580 and prior to 3.10 on the M340.

Remediation

Upgrade firmware to fixed versions: M580 to 2.90 or later; M340 to 3.10 or later.
If upgrading is not feasible, mitigate exposure: restrict Modbus write access to trusted systems, segment the PLC network, and deploy network controls (firewall/VPN) to limit who can reach the Modbus interface; disable or tightly control memory-write operations where possible; enforce least-privilege access for Modbus clients; monitor Modbus traffic for anomalous write attempts.
Validate the fix: after applying the firmware updates or mitigations, test Modbus write operations to ensure the DoS condition cannot be triggered and monitor for abnormal controller behavior.
Maintain alignment with vendor guidance: monitor Schneider Electric advisories and apply subsequent security updates as they are released.