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Wrc 1167gst2 FirmwareOperating system · Elecom

CVE-2021-20861

HIGH · 8.8 CVSS v3.1 Published 2021-12-01
Fix available
A fix is available. Upgrade to after 2.11 or later.
See remediation →
93/100
Remediation priority · Urgent
No privileges Zero-click

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
Improper access control vulnerability in ELECOM LAN routers (WRC-1167GST2 firmware v1.25 and prior, WRC-1167GST2A firmware v1.25 and prior, WRC-1167GST2H firmware v1.25 and prior, WRC-2533GS2-B firmware v1.52 and prior, WRC-2533GS2-W firmware v1.52 and prior, WRC-1750GS firmware v1.03 and prior, WRC-1750GSV firmware v2.11 and prior, WRC-1900GST firmware v1.03 and prior, WRC-2533GST firmware v1.03 and prior, WRC-2533GSTA firmware v1.03 and prior, WRC-2533GST2 firmware v1.25 and prior, WRC-2533GST2SP firmware v1.25 and prior, WRC-2533GST2-G firmware v1.25 and prior, and EDWRC-2533GST2 firmware v1.25 and prior) allows a network-adjacent authenticated attacker to bypass access restriction and to access the management screen of the product via unspecified vectors.

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

This vulnerability allows a network-adjacent authenticated attacker to bypass access restrictions on multiple ELECOM LAN router models and access the management interface. The improper access control flaw exists in the authentication/authorization mechanism that normally restricts management screen access to legitimate users.

MitigationApply vendor-provided firmware updates (v1.26+ for WRC-1167GST2 series, v1.53+ for WRC-2533GS2, v1.04+ for WRC-1750GS/WRC-1900GST/WRC-2533GST models, v2.12+ for WRC-1750GSV) as they become available. Until patched, restrict network access to trusted users 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 1167gst2 FirmwareOperating system
Affected:<= 1.25
Wrc 1167gst2a FirmwareOperating system
Affected:<= 1.25
Wrc 1167gst2h FirmwareOperating system
Affected:<= 1.25
Wrc 2533gs2 B FirmwareOperating system
Affected:<= 1.52
Wrc 2533gs2 W FirmwareOperating system
Affected:<= 1.52
Wrc 1750gs FirmwareOperating system
Affected:<= 1.03
Wrc 1750gsv FirmwareOperating system
Affected:<= 2.11
Wrc 1900gst FirmwareOperating system
Affected:<= 1.03

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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 the ELECOM router model
    Locate the model number on the device label or access the router's status page to confirm the exact model (Wrc-1167gst2, Wrc-1167gst2a, Wrc-1167gst2h, Wrc-2533gs2 B, Wrc-2533gs2 W, Wrc-1750gs, Wrc-1750gsv, or Wrc-1900gst)
    Affected if the model is any of the eight listed in the affected products
  2. Check the installed firmware version
    Access the router's web administration interface, navigate to the System or Firmware status section, and record the firmware version number displayed
    Affected if the firmware version is at or below 1.25 for WRC-1167GST2 series, at or below 1.52 for WRC-2533GS2 models, at or below 1.03 for WRC-1750GS/WRC-1900GST, or at or below 2.11 for WRC-1750GSV
  3. Verify if remote management is enabled
    In the router admin interface, locate the Remote Management, Remote Access, or WAN Access settings (usually under Advanced or Security sections) and confirm whether management interface access is permitted from WAN or non-local networks
    Affected if remote management or WAN access to the admin interface is enabled
  4. Confirm network exposure of management port
    From a system on an external network (or using an external port scan tool), attempt to reach the router's admin port (typically 80/443) via its public WAN IP or test if the management interface responds to requests from non-local IP addresses
    Affected if the router's web management interface is reachable from outside the local network

You are affected if you own one of the listed models, run an affected firmware version, AND have the management interface accessible from the network (remote management enabled or exposed WAN port).

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
Upgrade available Upgrade to a release after 2.11
Interim mitigation

Apply vendor-provided firmware updates (v1.26+ for WRC-1167GST2 series, v1.53+ for WRC-2533GS2, v1.04+ for WRC-1750GS/WRC-1900GST/WRC-2533GST models, v2.12+ for WRC-1750GSV) as they become available. Until patched, restrict network access to trusted users and consider network segmentation to limit exposure.

Fix this in Wrc 1167gst2 Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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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-2021-20861 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

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