CVE-2021-20859

Authenticated adjacent-network OS command execution

Published Dec 1, 2021 · Updated Aug 3, 2024

OS command injection in ELECOM LAN Routers allows remote authenticated users to execute arbitrary OS commands from an adjacent network. ELECOM and JVN identify the affected firmware and command-injection class but do not disclose the request handler, parameter, or unsafe command-building operation. Reachability requires valid router credentials and access from the adjacent network; successful exploitation grants command execution on the appliance.

CVSS severity8.0
High
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in ELECOM LAN Routers allows remote authenticated users to execute arbitrary OS commands from an adjacent network. ELECOM and JVN identify the affected firmware and command-injection class but do not disclose the request handler, parameter, or unsafe command-building operation. Reachability requires valid router credentials and access from the adjacent network; successful exploitation grants command execution on the appliance.

The record

CVE
CVE-2021-20859
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
ELECOM CO., LTD.
Product
ELECOM LAN Routers
Classifications
CWE-78, T1059
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=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

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

ELECOM CO., LTD. · ELECOM LAN Routersversion=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

Published CVSS scores

7.7NIST NVDAV:A/AC:L/Au:S/C:C/I:C/A:C
7.7JPCERT/CC and IPA JVNAV:A/AC:L/Au:S/C:C/I:C/A:C
8.0NIST NVDCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.0JPCERT/CC and IPA JVNCVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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