CVE-2021-39279Public exploitNetwork attack vector

Authenticated OS command execution via TFTP parameters

Published Sep 7, 2021 · Updated Aug 4, 2024

Command injection in Moxa WAC, OnCell, TAP, and WDR devices allows remote authenticated users to execute OS commands through the web interface. The /forms/web_importTFTP CGI handler accepts unneutralized servIP, configPath, and fileName values during TFTP import and incorporates them into operating-system commands. A valid web session and crafted TFTP import request are required; successful exploitation compromises the device operating system.

CVSS severity8.8
High
EPSS probability4.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Moxa WAC, OnCell, TAP, and WDR devices allows remote authenticated users to execute OS commands through the web interface. The /forms/web_importTFTP CGI handler accepts unneutralized servIP, configPath, and fileName values during TFTP import and incorporates them into operating-system commands. A valid web session and crafted TFTP import request are required; successful exploitation compromises the device operating system.

The record

CVE
CVE-2021-39279
Published
Sep 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
9.0NIST NVDAV:N/AC:L/Au:S/C:C/I:C/A:C

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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

Public exploit references

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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