Actively exploited · Published Jun 11, 2021 · Assigned by mitre
CVE-2021-26829
Medium 5.4 Exploited
In plain English
A medium-severity cross-site scripting in ScadaBR from OpenPLC. Attackers are actively exploiting it in the wild (listed by CISA on November 28, 2025). The chance it is exploited in the next 30 days is estimated at 48.0% (higher than 99% of all known vulnerabilities). Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA guidance
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Federal agencies must remediate by Dec 19, 2025.
Official description
OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm.
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
References
- https://youtu.be/Xh6LPCiLMa8 x_refsource_MISC
- http://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4 x_refsource_MISC
- https://www.forescout.com/blog/anatomy-of-a-hacktivist-attack-russian-aligned-group-targets-otics/ third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26829 government-resource