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CVE-2021-26829

MEDIUM
5.4
CVSS Score
Published: June 11, 2021 at 11:05 AM UTC
Updated: June 17, 2026 at 03:43 AM UTC
1 product affected across 1 vendorScadaBR

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Severity
MEDIUM5.4
Exploitation
CISA KEV
Exploit prediction
EPSS 48%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score48.0%

EPSS (Exploit Prediction Scoring System) estimates a 48.0% chance this CVE is exploited in the wild within the next 30 days — higher than 99% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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

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.
Ransomware Use
Unknown
Added to KEV
Nov 28, 2025
Remediation Due
Dec 19, 2025
316 days overdue
Notes
This vulnerability could affect an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: https://github.com/SCADA-LTS/Scada-LTS/pull/3211
https://nvd.nist.gov/vuln/detail/CVE-2021-26829

Description

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

ScadaBR· Scadabr
95%
v ≤ 0.9.1v ≤ 1.12.4
linux-linux-kernel (environment) · microsoft-windows (environment)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (4)

x_refsource_MISCVendor Advisory
Source: [email protected]
http://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4
x_refsource_MISCExploitThird Party Advisory
Source: [email protected]
https://youtu.be/Xh6LPCiLMa8
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26829
Third Party Advisory
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.forescout.com/blog/anatomy-of-a-hacktivist-attack-russian-aligned-group-targets-otics/

SSVC — Action Prioritization

SSVCActiveNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.4MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79

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