CVE-2021-20739

Unauthenticated OS command execution

Published Jul 7, 2021 · Updated Aug 3, 2024

OS command injection in all versions of eleven ELECOM WRC and WRH router models allows remote attackers to execute arbitrary OS commands. The vendor describes an authentication deficiency that exposes command execution but does not identify the affected interface, input, or command-building operation. Exploitation requires reachability from an adjacent network and no authentication; public advisories do not specify command privileges or persistence.

CVSS severity6.3
Medium
EPSS probability0.51%
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 all versions of eleven ELECOM WRC and WRH router models allows remote attackers to execute arbitrary OS commands. The vendor describes an authentication deficiency that exposes command execution but does not identify the affected interface, input, or command-building operation. Exploitation requires reachability from an adjacent network and no authentication; public advisories do not specify command privileges or persistence.

The record

CVE
CVE-2021-20739
Published
Jul 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, CAPEC-88, T1059
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 7, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
6.3JPCERT/CCCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
5.8NIST NVDAV:A/AC:L/Au:N/C:P/I:P/A:P

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CAPEC-88OS 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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