CVE-2021-26829: OpenPLC ScadaBR stored XSS in system_settings.shtm

CVE-2021-26829 · Severity: critical · CVSS 5.4 · Exploited in the wild · Published 2025-11-28

OpenPLC ScadaBR, a software platform used for industrial automation and monitoring, contains a security flaw that allows attackers to inject malicious scripts into the system's management interface. If an administrative user views the affected settings page, the attacker could hijack their session, potentially leading to unauthorized changes in industrial processes or data theft. This vulnerability has been observed being used in active attacks against industrial infrastructure.

Technologies: OpenPLC SCADABr. Vendors: OpenPLC.

Quick answers

Is CVE-2021-26829 exploited in the wild?
Yes. CVE-2021-26829 is known to be exploited in the wild, first recorded on 28 November 2025. Treat it as urgent.
How severe is CVE-2021-26829?
Critical severity, with a CVSS score of 5.4, published 28 November 2025.
Which products and versions are affected?
OpenPLC ScadaBR Linux up to 0.9.1, Windows up to 1.12.4.
Is there a fix for CVE-2021-26829?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2021-26829 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2021-26829?
Check whether you run OpenPLC SCADABr. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A stored cross-site scripting (XSS) vulnerability exists in OpenPLC ScadaBR through version 0.9.1 (Linux) and 1.12.4 (Windows) within the 'system_settings.shtm' page. The application fails to properly neutralize user-supplied input before it is stored and subsequently rendered to other users. An authenticated attacker with low privileges can inject malicious JavaScript that executes when an administrator or another user visits the settings page. This can lead to session hijacking, unauthorized configuration changes, or further exploitation of the SCADA environment. This vulnerability is listed in the CISA KEV catalog, indicating active exploitation in the wild.

Affected products

  • OpenPLC ScadaBR Linux up to 0.9.1, Windows up to 1.12.4

Timeline

  • 2021-06-11: disclosed: Initial NVD publication
  • 2025-11-28: kev added: Added to CISA Known Exploited Vulnerabilities catalog
  • 2025-11-28: exploited: Confirmed active exploitation in the wild

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.