CVE-2021-43936Public exploitNetwork attack vector

Authenticated code execution via unrestricted PHP upload

Published Dec 6, 2021 · Updated Aug 4, 2024

Unrestricted file upload in Distributed Data Systems WebHMI before 4.1 allows remote authenticated users to execute arbitrary code. The files.php handler accepts a PHP payload without blocking executable file types and stores it beneath the web-accessible uploads/files path. Exploitation requires a valid application session; requesting the uploaded script then runs attacker-supplied commands in the appliance environment.

CVSS severity10.0
Critical
EPSS probability35.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in Distributed Data Systems WebHMI before 4.1 allows remote authenticated users to execute arbitrary code. The files.php handler accepts a PHP payload without blocking executable file types and stores it beneath the web-accessible uploads/files path. Exploitation requires a valid application session; requesting the uploaded script then runs attacker-supplied commands in the appliance environment.

The record

CVE
CVE-2021-43936
Published
Dec 6, 2021
Updated
Aug 4, 2024
Vendor
Distributed Data Systems
Product
WebHMI
Classifications
CWE-434, T1190, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 6, 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?

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

  1. Affected versionversion=4.1 <4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Distributed Data Systems · WebHMIversion=4.1 <4.1

Published CVSS scores

10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application
T1505.003Server Software Component: Web Shell

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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