CVE intelligence and bounded remediation

CVE-2020-7540 — Schneider-Electric Modicon M340 Bmxp341000 Firmware security vulnerability

Critical CVSS 9.8

A CWE-306: Missing Authentication for Critical Function vulnerability exists in the Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions), that could cause unauthenticated command execution in the controller when sending special HTTP requests.

Severity
Critical
CVSS
9.8 (3.1)
Published
2020-12-11
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-306

Affected products

  • schneider-electric / modicon_m340_bmxp341000_firmware
  • schneider-electric / modicon_m340_bmxp342000_firmware
  • schneider-electric / modicon_m340_bmxp3420102_firmware
  • schneider-electric / modicon_m340_bmxp3420102cl_firmware
  • schneider-electric / modicon_m340_bmxp342020_firmware
  • schneider-electric / modicon_m340_bmxp3420302_firmware

Showing 6 representative product identities from 23 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.