CVE-2021-26828
OpenPLC ScadaBR Unrestricted Upload of File with Dangerous Type Vulnerability
OpenPLC ScadaBR
OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows remote authenticated users to upload and execute arbitrary JSP files via view_edit.shtm.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 3 December 2025. US federal agencies were required to remediate it by 24 December 2025.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 39.1%, which is higher than 98.6% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2021-26828 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2021-26828.
What does CVE-2021-26828 affect?
CVE-2021-26828 affects OpenPLC ScadaBR. OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows remote authenticated users to upload and execute arbitrary JSP files via view_edit.shtm.
How severe is CVE-2021-26828?
CVE-2021-26828 is rated HIGH with a CVSS base score of 8.8. EPSS puts the probability of exploitation in the next 30 days at 39.1%, higher than 98.6% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 24 December 2025.
How should organisations respond to CVE-2021-26828?
Apply the vendor patch for OpenPLC ScadaBR as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.