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Wrc 300febk A FirmwareOperating system · Elecom

CVE-2021-20646

MEDIUM · 6.5 CVSS v3.1 Published 2021-02-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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 request forgery (CSRF) vulnerability in ELECOM WRC-300FEBK-A allows remote attackers to hijack the authentication of administrators and execute an arbitrary request via unspecified vector. As a result, the device settings may be altered and/or telnet daemon may be started.

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 · moderate confidence

Cross-site request forgery (CSRF) vulnerability in ELECOM WRC-300FEBK-A router allows remote attackers to hijack authenticated administrator sessions by tricking the browser into sending malicious requests. Successful exploitation enables attackers to alter device settings or start the telnet daemon, potentially creating a backdoor into the network.

MitigationApply vendor firmware update when available; until then, avoid accessing the router admin panel while browsing untrusted sites, and consider network segmentation to limit exposure.

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
Wrc 300febk A FirmwareOperating system
Affected:all versions

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
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/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. Confirm the router model is Elecom WRC-300FEBK-A
    Log into the router web admin interface (typically at 192.168.1.1 or 192.168.0.1) and navigate to the status or system information page to verify the exact model name displayed.
    Affected if The displayed model name is exactly 'WRC-300FEBK-A' (or WRC-300FEBK). This confirms you have the affected hardware.
  2. Verify the installed firmware version
    In the router admin panel, locate the firmware version or software version field (usually under Status, System, or Maintenance sections).
    Affected if Any firmware version is displayed, because the vendor advisory states all versions of this specific model are affected by CVE-2021-20646.
  3. Check if remote web management is enabled
    In the router admin panel, go to the remote management or access control settings (often under Advanced, Security, or Administration). Look for options labeled 'Remote Management', 'Web Access from WAN', or 'HTTP/WEB Remote Access'.
    Affected if Remote management is enabled and the admin interface is accessible from the WAN/internet side, which increases exposure to CSRF attacks from malicious external sites.
  4. Verify telnet service status
    Attempt to connect to the router's LAN IP on port 23 using telnet (e.g., 'telnet 192.168.1.1') or check the router's service list in the admin panel if available.
    Affected if Telnet service is unexpectedly running or accessible, as CVE-2021-20646 specifically mentions the vulnerability can be exploited to start the telnet daemon as a potential backdoor.
  5. Review admin account for unauthorized changes
    Check the router's administrator account settings, port forwarding rules, and firewall settings for any unexpected configurations or newly added rules.
    Affected if Any unexplained changes exist, as CSRF attacks can silently modify router settings without the administrator's direct knowledge.

If your device is confirmed to be an Elecom WRC-300FEBK-A router running any firmware version and the admin interface is accessible (locally or remotely), your environment is affected by CVE-2021-20646.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor firmware update when available; until then, avoid accessing the router admin panel while browsing untrusted sites, and consider network segmentation to limit exposure.

Fix this in Wrc 300febk A Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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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-2021-20646 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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