CVE-2021-26829

MEDIUMNVD 5.49.0▲Trending — 4 sources updated this weekExploited in the wild

5.4

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

CVSS v3: 5.4
EG Score: 9.0(high)
EPSS: 92.0%
KEV: ⚠ Exploited

Published

June 11, 2021

Last Modified

December 1, 2025

References (6)

cve@mitrehttp://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4
cve@mitrehttps://youtu.be/Xh6LPCiLMa8
af854a3a-2127-422b-91ae-364da2661108http://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4
af854a3a-2127-422b-91ae-364da2661108https://youtu.be/Xh6LPCiLMa8
134c704f-9b21-4f2e-91b3-4a467353bcc0https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26829
134c704f-9b21-4f2e-91b3-4a467353bcc0https://www.forescout.com/blog/anatomy-of-a-hacktivist-attack-russian-aligned-group-targets-otics/

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-79Cross-site Scripting (XSS)

Data Freshness Timeline

(refreshed 20× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-06-10 03:27 UTCEG score recompute
2026-06-10 03:27 UTCGHSA enrichment
2026-06-09 23:24 UTCEG score recompute
2026-06-09 23:24 UTCGHSA enrichment
2026-06-09 19:20 UTCEG score recompute
2026-06-09 19:20 UTCGHSA enrichment
2026-06-09 18:42 UTCCISA KEV update
2026-06-09 17:12 UTCCISA KEV update
2026-06-09 15:17 UTCEG score recompute
2026-06-09 15:17 UTCGHSA enrichment
2026-06-09 11:13 UTCEG score recompute
2026-06-09 11:13 UTCGHSA enrichment
2026-06-09 07:10 UTCEG score recompute
2026-06-09 07:09 UTCGHSA enrichment
2026-06-09 03:06 UTCEG score recompute
2026-06-09 03:05 UTCGHSA enrichment
2026-06-08 23:02 UTCEG score recompute
2026-06-08 23:02 UTCGHSA enrichment
2026-06-08 19:16 UTCCISA KEV update
2026-06-08 18:58 UTCEG score recompute

Frequently asked(6)

What is CVE-2021-26829?

CVE-2021-26829 is a medium vulnerability published on June 11, 2021. OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm.

When was CVE-2021-26829 disclosed?

CVE-2021-26829 was first published in the National Vulnerability Database on June 11, 2021, with the most recent update on December 1, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-26829 actively exploited?

Yes. CISA added CVE-2021-26829 to the Known Exploited Vulnerabilities catalog on November 28, 2025, affecting OpenPLC ScadaBR. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.

What is the CVSS score of CVE-2021-26829?

CVE-2021-26829 has a CVSS v3 base score of 5.4 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.

Which products are affected by CVE-2021-26829?

CVE-2021-26829 affects OpenPLC ScadaBR. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.

How do I remediate CVE-2021-26829?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-26829, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-26829

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CVE-2021-26829

📅 Published

🔄 Last Modified

🔗 References (6)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(6)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-26829?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (6)

Frequently asked(6)

Related CVEs(same CWE)