---
id: "CVE-2021-26829"
kind: "vulnerability"
aliases: ["CVE-2021-26829"]
title: "OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm"
severity: "medium"
cvss: 5.4
epss: null
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "OpenPLC ScadaBR", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "scadabr", "fixed": [], "affected": "<= 0.9.1", "ecosystem": "vendor"}, {"name": "scadabr", "fixed": [], "affected": "<= 1.12.4", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "industrial-control", "infrastructure", "openplc", "scadabr", "self-hosted"]
not_affected_if: ["not-running-scadabr"]
published_at: "2021-06-11T12:15:12+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:51+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-26829", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-26829", "first_seen_at": "2026-10-23T23:44:51+00:00"}]
---

# OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm

OpenPLC ScadaBR has a reflected or stored cross-site scripting flaw in its system_settings.shtm page. An attacker can run script in the browser of a logged-in user who opens a crafted page, which CISA lists as actively exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:OpenPLC ScadaBR affected ? fixed ?
- vendor:scadabr affected <= 0.9.1 fixed ?
- vendor:scadabr affected <= 1.12.4 fixed ?

## Fix

Apply vendor mitigations per CISA guidance, or discontinue use of ScadaBR if no mitigation is available.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-26829
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-26829

## From the sources

OpenPLC ScadaBR contains a cross-site scripting vulnerability via system_settings.shtm.

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_