Security Alert: Critical Vulnerability Hits Anritsu Remote Spectrum Monitors

CISA and related reporting describe CVE-2026-3356, a critical (CVSS 9.8) design flaw in Anritsu Remote Spectrum Monitor models MS27100A–MS27103A that lacks any mechanism for authentication; as a result, any network user can access and control the device management interface. Anritsu has stated it will not provide a firmware update and recommends deploying these devices only within protected networks, leaving affected deployments with a persistent high-risk exposure capable of enabling configuration changes, data interception, or denial of monitoring capability.