CVE-2021-26828Known exploitationPublic exploitNetwork attack vector

Authenticated code execution via unrestricted JSP upload

Published Jun 11, 2021 · Updated Dec 4, 2025

File upload in OpenPLC ScadaBR 0.9.1 and earlier on Linux and 1.12.4 and earlier on Windows allows remote authenticated users to execute code. The view_edit.shtm upload handler fails to restrict executable file types, allowing the servlet container to process an uploaded JSP as server-side code. A valid application account and network access to the endpoint are required; successful exploitation runs attacker-supplied JSP code on the server.

CVSS severity8.8
High
EPSS probability39.36%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

File upload in OpenPLC ScadaBR 0.9.1 and earlier on Linux and 1.12.4 and earlier on Windows allows remote authenticated users to execute code. The view_edit.shtm upload handler fails to restrict executable file types, allowing the servlet container to process an uploaded JSP as server-side code. A valid application account and network access to the endpoint are required; successful exploitation runs attacker-supplied JSP code on the server.

The record

CVE
CVE-2021-26828
Published
Jun 11, 2021
Updated
Dec 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Dec 4, 2025Record 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
8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/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)
Vectornetwork
Privilegesauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application

Public exploit references

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

Reported exploitation

Technologies

Your stack

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Your stack

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