VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 28 November 2025Ransomware use: unknown
OpenPLC ScadaBR

CVE-2021-26829: OpenPLC ScadaBR Cross-site Scripting Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 28 Nov 2025, 1,631 days after the CVE record was published.

How likely is exploitation in the next 30 days?
48.1%

EPSS score, percentile 98.9 of all scored records

How severe?
5.4 Medium

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 19 Dec 2025. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

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 due date for this action: 19 December 2025.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

Affected products and versions

The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

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

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2021-26829 to its Known Exploited Vulnerabilities (KEV) catalog on 28 Nov 2025.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 19 Dec 2025.
  • The CVE record was published on 11 Jun 2021, 1,631 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 5.4 (Medium), taken from CISA's enrichment of the record.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 48.1% (percentile 98.9), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

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

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
11 Jun 2021CVE record published
28 Nov 2025Added to CISA KEV
2 Dec 2025CVE record last updated
19 Dec 2025CISA due date for the required action

References

More exploited OpenPLC vulnerabilities

  • CVE-2021-26828: OpenPLC ScadaBR Unrestricted Upload of File with Dangerous Type Vulnerability (added 3 Dec 2025)