CVE-2021-26829KEV · OVERDUE

OpenPLC ScadaBR Cross-site Scripting Vulnerability

Medium · published June 11, 2021

Patch now

The score understates this — it's already being exploited

CVSS calls it medium at 5.4. It is confirmed in active exploitation. It sits in the 98.9th percentile for exploit probability.

309
days past CISA
deadline
CVSS v3.1
5.4
EPSS
48%
Percentile
98.9
In the wild
Confirmed
What it is

⚠️ Beware of sneaky scripts slipping into your settings! This stored XSS vulnerability in OpenPLC ScadaBR could let attackers inject harmful code through the system_settings.shtm page. 😱 Think of it like a guest slipping a fake menu item into your restaurant's order pad — if the kitchen doesn’t check it, they might serve up a nasty surprise to customers who thought they were ordering a regular dish! 🍽️ An attacker could exploit this vulnerability to execute malicious scripts within your environment, potentially stealing sensitive data or hijacking user sessions. While it’s not the worst-case scenario, the risk of a breach could lead to an unfortunate reputation disaster! ⚠️

Put simply

Think of it like a guest slipping a fake menu item into your restaurant's order pad — if the kitchen doesn’t check it, they might serve up a nasty surprise to customers who thought they were ordering a regular dish! 🍽️ This stored XSS vulnerability allows an attacker to insert malicious JavaScript via the system_settings.shtm page, impacting both Linux and Windows versions of OpenPLC ScadaBR up to specific versions. If unchecked, this can lead to unauthorized actions in the web interface.

What to do

An attacker could exploit this vulnerability to execute malicious scripts within your environment, potentially stealing sensitive data or hijacking user sessions. While it’s not the worst-case scenario, the risk of a breach could lead to an unfortunate reputation disaster! ⚠️ To secure your installations, upgrade OpenPLC ScadaBR to the latest version. Be sure to sanitize inputs on the settings page to prevent script injection. Regularly audit your web applications for similar vulnerabilities! 🔒 You've got this! Implement these fixes and continue being a security hero! 🦸‍♂️

The record
Technical detail
CVSS v3.1
5.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.48050 · 98.9th percentile
Published
2021-06-11T11:05Z
KEV added
2025-11-28 · due 2025-12-19
EPSS history
Timeline
  • 28 NOV 00:00Z
    Added to CISA KEV — remediate by Dec 19
    kev
  • 11 JUN 11:05Z
    OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm
    cvelistv5