medium Known exploitedREV. 01

CVE-2021-26829OpenPLC ScadaBR — stored script injection in system settings

OpenPLC ScadaBR through 0.9.1 on Linux and 1.12.4 on Windows stores script from the system settings page and runs it in the next operator's session. Hacktivist crews have used it against operational sites.

YOUR NEXT MOVE

Move to a maintained supervisory control build now; keep the interface off routable networks and review settings pages for content nobody entered.

Read the risk

THE VITAL STATS
CVSS score
5.4/ 10
CVSS v3.1
EPSS probability
48%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2021-06-11
Added to KEV
2025-11-28
Exploit published
Yes
Confidence
high
Kill chain
execution
MITRE ATT&CK
T1059.007
Severity
medium

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

Attacker needsThe ability to store content on the settings page, and an operator who later opens it.

Behind the card

5 REFERENCES
Field-level provenanceTRACE THE SOURCES +

Which source supports each field, when it was retrieved, and who extracted it.

FieldsSourceRetrievedExtractorConfidence
cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_atnvd.nist.gov2026-09-24scrty-crds-pipeline/0.1high
exploitation.known_exploited, exploitation.kev_addedcisa.gov2026-09-24scrty-crds-pipeline/0.1high
epssapi.first.org2026-09-24scrty-crds-pipeline/0.1high
title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisitesnvd.nist.gov2026-09-24claude-codehigh

Printing history

THE RECORD
  1. r1Initial base card

First printing. This card has not been reprinted since publication.

crds:cve-2021-26829 · CRDS 0.1 · Issued 2026-09-24