CVE-2021-26828 OpenPLC ScadaBR: dangerous file upload
In plain words: The program accepts files it should refuse, such as programs disguised as ordinary uploads. The attacker can place and run their own tools on the server.
Confirmed exploited by CISA on · US federal patch deadline Dec 24, 2025
What to do
- Install OpenPLC's security update for ScadaBR. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Keep a list of every internet-facing server you run so nothing is forgotten.
- Patch anything in this catalog first, ahead of normal patch cycles.
- Put admin and file-transfer apps behind a VPN or single sign-on instead of the open internet.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: Mass data theft and ransomware: a single flaw in a file-transfer or email server has exposed thousands of organisations at once.
The details
- Official name
- OpenPLC ScadaBR Unrestricted Upload of File with Dangerous Type Vulnerability
- Product
- OpenPLC ScadaBR
- CISA description
- OpenPLC ScadaBR contains an unrestricted upload of file with dangerous type vulnerability that allows remote authenticated users to upload and execute arbitrary JSP files via view_edit.shtm.
- Type of flaw
- Dangerous file upload (CWE-434)
- Confirmed exploited
- Dec 3, 2025
- US federal patch deadline
- Dec 24, 2025
Ask Cleus about it
Ask about a vulnerability, an update, a weird message, or the news. Plain-word answers, free, no account.
Answering about CVE-2021-26828 ·
Questions about CVE-2021-26828
Is CVE-2021-26828 being exploited?
Yes. CISA added CVE-2021-26828 to its Known Exploited Vulnerabilities catalog on Dec 3, 2025, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2021-26828?
Install OpenPLC's security update for ScadaBR. If no update exists, follow the vendor's workaround or stop using the product until one ships. Keep a list of every internet-facing server you run so nothing is forgotten.
Am I affected by CVE-2021-26828?
Only if you use OpenPLC ScadaBR. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.