CVE entry · CVE-2021-26829
CVE-2021-26829: OpenPLC ScadaBR Cross-site Scripting Vulnerability
OpenPLC ScadaBR contains a cross-site scripting vulnerability via system_settings.shtm.
- Actively exploited: added to CISA’s KEV catalog on November 28, 2025.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: December 19, 2025.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes OpenPLC ScadaBR, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.