CVE-2021-20853

Administrator command execution through management screen

Published Dec 1, 2021 · Updated Aug 3, 2024

OS command injection in ELECOM WRH-733GBK/GWH firmware 1.02.9 and earlier allows remote authenticated users to execute commands from the LAN. The public advisories do not identify the affected management-screen handler or the input that reaches an operating-system command. Exploitation requires administrator access to the management screen from the adjacent LAN and grants command execution on the router.

CVSS severity6.8
Medium
EPSS probability0.42%
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 WRH-733GBK/GWH firmware 1.02.9 and earlier allows remote authenticated users to execute commands from the LAN. The public advisories do not identify the affected management-screen handler or the input that reaches an operating-system command. Exploitation requires administrator access to the management screen from the adjacent LAN and grants command execution on the router.

The record

CVE
CVE-2021-20853
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
ELECOM CO., LTD.
Product
ELECOM LAN Routers
Classifications
CWE-78, T1059
Attack vector
adjacent
Privileges
admin

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=WRH-733GBK firmware v1.02.9 and prior and WRH-733GWH firmware v1.02.9 and prior

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesadmin

What is affected?

ELECOM CO., LTD. · ELECOM LAN Routersversion=WRH-733GBK firmware v1.02.9 and prior and WRH-733GWH firmware v1.02.9 and prior

Published CVSS scores

5.2NIST NVDAV:A/AC:L/Au:S/C:P/I:P/A:P
6.8JPCERT/CCCVSS:3.0/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
5.2JPCERT/CCAV:A/AC:L/Au:S/C:P/I:P/A:P
6.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:H/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
Privilegesadmin
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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