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PatchSiren cyber security CVE debrief

CVE-2026-3356 Anritsu CVE debrief

CVE-2026-3356 is a critical authentication bypass affecting the Anritsu Remote Spectrum Monitor MS27102A. The advisory states that the device provides no mechanism to enable or configure authentication, making the issue inherent to the product design and leaving exposure dependent on network placement and access controls rather than a simple configuration change.

Vendor
Anritsu
Product
Remote Spectrum Monitor MS27100A
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-31
Original CVE updated
2026-03-31
Advisory published
2026-03-31
Advisory updated
2026-03-31

Who should care

Operators and defenders responsible for Anritsu Remote Spectrum Monitor deployments, especially industrial control system and OT environments where the management interface may be reachable from shared or untrusted networks.

Technical summary

According to the CISA advisory, unauthorized users can access and manipulate the MS27102A management interface because authentication can be bypassed and cannot be enabled or configured on the device. The source rates the issue with CVSS 3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating remote, unauthenticated impact across confidentiality, integrity, and availability. CISA also notes that Anritsu has no plans to fix the issue and recommends deploying the product only within secure network environments.

Defensive priority

Immediate

Recommended defensive actions

  • Restrict management interface exposure to trusted, segmented networks only.
  • Do not place affected devices on directly reachable or internet-accessible networks.
  • Review firewall, ACL, and routing controls to limit who can reach the management interface.
  • Treat the device as lacking built-in authentication and compensate with external network controls.
  • Follow CISA ICS recommended practices and defense-in-depth guidance for OT environments.
  • Contact Anritsu Technical Support at 1-800-267-4878 for vendor guidance.

Evidence notes

The source advisory explicitly says the MS27102A has an authentication bypass, that unauthorized users can access and manipulate the management interface, and that there is no mechanism to enable or configure authentication. It also states Anritsu has no plans to fix the issue and recommends deployment only within secure network environments. The advisory’s SSVC note is included as provided: SSVCv2/E:N/A:Y/2026-03-30T06:00:00.000000Z.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-3356 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-3356

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-3356 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-3356

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2026/icsa-26-090-01.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-090-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/uscert/ics/alerts/ICS-ALERT-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/publications/Cybersecurity_Best_Practices_for_Industrial_Control_Systems.pdf

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/topics/industrial-control-systems

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-alerts/ics-alert-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.