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Rtx830 FirmwareOperating system · Yamaha

CVE-2021-20843

MEDIUM · 5.4 CVSS v3.1 Published 2021-11-24
Fix available
A fix is available. Upgrade to 15.01.18 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Cross-site script inclusion vulnerability in the Web GUI of RTX830 Rev.15.02.17 and earlier, NVR510 Rev.15.01.18 and earlier, NVR700W Rev.15.00.19 and earlier, and RTX1210 Rev.14.01.38 and earlier allows a remote authenticated attacker to alter the settings of the product via a specially crafted web page.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Cross-site script inclusion (XSSI) vulnerability in the Web GUI of Yamaha RTX830, NVR510, NVR700W, and RTX1210 routers allows a remote authenticated attacker to alter device settings by tricking an authenticated user into visiting a specially crafted web page that includes malicious scripts.

MitigationApply vendor firmware updates: RTX830 to Rev.15.02.18 or later, NVR510 to Rev.15.01.19 or later, NVR700W to Rev.15.00.20 or later, and RTX1210 to Rev.14.01.39 or later.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Rtx830 FirmwareOperating system
Affected:<= 15.02.17
Nvr510 FirmwareOperating system
Affected:<= 15.01.18
Nvr700w FirmwareOperating system
Affected:<= 15.00.19
Rtx1210 FirmwareOperating system
Affected:<= 14.01.38
Biz Box Rtx830 FirmwareOperating system
Affected:<= 15.02.17
Biz Box Nvr510 FirmwareOperating system
Affected:< 15.01.18
Biz Box Nvr700w FirmwareOperating system
Affected:<= 15.00.19
Biz Box Rtx1210 FirmwareOperating system
Affected:<= 14.01.38

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify router model
    Access the router via console/SSH and execute 'show environment' or check the web GUI login page for the model name
    Affected if Model is RTX830, NVR510, NVR700W, or RTX1210 (or their NTT West Biz Box variants)
  2. Check installed firmware version
    Execute 'show version' via console/SSH or check the router status page in the web GUI to locate the firmware revision number
    Affected if Firmware version is at or below 15.02.17 for RTX830, 15.01.18 for NVR510, 15.00.19 for NVR700W, or 14.01.38 for RTX1210
  3. Confirm Web GUI is enabled
    Execute 'show config' and look for 'http server' or 'http gui' commands, or check if the router responds on HTTP/HTTPS ports (typically 80/443)
    Affected if HTTP or HTTPS server is configured and active on the router

If the router model is affected and the installed firmware version falls within the vulnerable ranges listed, and the Web GUI HTTP server is enabled, the device is affected by this XSSI vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 15.01.18 or later
Fixed in 15.01.18
Interim mitigation

Apply vendor firmware updates: RTX830 to Rev.15.02.18 or later, NVR510 to Rev.15.01.19 or later, NVR700W to Rev.15.00.20 or later, and RTX1210 to Rev.14.01.39 or later.

Recommended fix Moderate confidence

RTX830: Rev.15.02.18+ | NVR510: Rev.15.01.19+ | NVR700W: Rev.15.00.20+ | RTX1210: Rev.14.01.39+

  1. 1. Identify the exact model (RTX830, NVR510, NVR700W, RTX1210, or Biz Box variants) from the affected device.
  2. 2. Access the device's administration interface or use the Yamaha CLI/console.
  3. 3. Download the firmware update from the official Yamaha support page (www.rtpro.yamaha.co.jp) or your NTT EAST/WEST business portal if provided by your ISP.
  4. 4. Upload and apply the firmware update: For RTX830, upgrade to Rev.15.02.18 or later; For NVR510, upgrade to Rev.15.01.19 or later; For NVR700W, upgrade to Rev.15.00.20 or later; For RTX1210, upgrade to Rev.14.01.39 or later.
  5. 5. After upgrade, verify the device is operational and settings are intact.
  6. 6. Consider reviewing admin accounts and monitoring for unauthorized changes, as this XSSI vulnerability could have been exploited.
Caveat Standard firmware update risks apply - ensure backup of configuration before upgrading; some settings may need reconfiguration after firmware change

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Rtx830 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-20843 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data