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PatchSiren cyber security CVE debrief

CVE-2016-9366 Moxa CVE debrief

CVE-2016-9366 is a critical authentication-bypass issue in multiple Moxa NPort firmware lines. The vulnerability allows a network attacker to use brute force to determine parameters needed to bypass authentication, and NVD rates the impact as CVSS 9.8 with high confidentiality, integrity, and availability impact.

Vendor
Moxa
Product
Unknown
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2016-09-04
Original CVE updated
2025-06-05
Advisory published
2016-09-04
Advisory updated
2025-06-05

Who should care

Organizations running Moxa NPort serial-to-Ethernet device servers, especially OT/ICS environments and any network team exposing these devices to untrusted or broadly reachable networks.

Technical summary

According to the NVD record, affected Moxa NPort firmware branches include multiple product series prior to their fixed versions. The core issue is that an attacker can freely brute force parameters needed to bypass authentication. NVD assigns CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H and lists CWE-264. Because the attack requires no privileges and no user interaction, exposure on reachable networks materially raises risk.

Defensive priority

Immediate

Recommended defensive actions

  • Identify all Moxa NPort devices and verify exact series and firmware versions against the affected ranges in the NVD record.
  • Upgrade to the first fixed firmware versions listed by the vendor/NVD for each affected NPort series.
  • Restrict network access to management interfaces and place device servers behind trusted administrative networks or VPNs where possible.
  • Monitor for unusual authentication activity, repeated login attempts, or configuration changes on exposed devices.
  • If a device cannot be patched promptly, compensate with segmentation, ACLs, and strict administrative access controls until remediation is complete.

Evidence notes

CVE published by NVD on 2017-02-13T21:59:02.253Z and last modified on 2026-05-13T00:24:29.033Z. The supplied NVD data states that an attacker can freely use brute force to determine parameters needed to bypass authentication. NVD assigns CVSS 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) and lists CWE-264. Affected versions span multiple Moxa NPort series, with fixed-version cutoffs recorded in the NVD CPE criteria. The KEV field in the supplied data is false.

Sources and references

Verified primary and authoritative sources

  • CVE-2016-9366 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2016-9366

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

  • CVE-2016-9366 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2016-9366

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

Supplemental references

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.