CVE-2021-26829

Name: CVE-2021-26829
Creator: NVD / NIST
Published: 2021-06-11T12:15:12.053+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10Actively ExploitedEPSS 48.05%

Last modified Jun 17, 2026

CVE-2021-26829 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm.. CISA has confirmed active exploitation in the wild. EPSS estimates a 48.05% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

48.05%

98.7th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Dec 19, 2025.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Scadabr	Scadabr	<= 0.9.1
Scadabr	Scadabr	<= 1.12.4

References

http://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4Vendor Advisory
https://youtu.be/Xh6LPCiLMa8Exploit, Third Party Advisory
http://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4Vendor Advisory
https://youtu.be/Xh6LPCiLMa8Exploit, Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26829US Government Resource
https://www.forescout.com/blog/anatomy-of-a-hacktivist-attack-russian-aligned-group-targets-otics/Third Party Advisory

Timeline

Published: Jun 11, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-26829?

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

How severe is CVE-2021-26829?

CVE-2021-26829 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 48.05% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2021-26829?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26829?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST