CVE-2021-26829

CRITICALNVD 5.49.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2025-11-28), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 5.4 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 48%CVSS: 5.4Exploit: cisa kev · ssvc active · epss top5pctExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
48%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

June 11, 2021

Last Modified

December 1, 2025

Advisory Details (4)

Auto-updated Jun 13, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
generic

Anatomy of a Hacktivist Attack: Russia-Aligned Group Targets OT/ICS

https://www.forescout.com/blog/anatomy-of-a-hacktivist-attack-russian-aligned-group-targets-otics/
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26829
generic
https://youtu.be/Xh6LPCiLMa8
generic

[REPORT] Falhas de segurança em versões do ScadaBR - #4 de h3v0x - ScadaBR - Geral - ScadaBR

http://forum.scadabr.com.br/t/report-falhas-de-seguranca-em-versoes-do-scadabr/3615/4

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 59× in last 7d / 240× 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.

Showing the most recent 100 of 921 total refreshes for this CVE.

  1. 2026-09-25 12:24 UTCGHSA enrichment
  2. 2026-09-25 08:20 UTCGHSA enrichment
  3. 2026-09-25 04:13 UTCGHSA enrichment
  4. 2026-09-25 00:09 UTCGHSA enrichment
  5. 2026-09-24 20:05 UTCGHSA enrichment
  6. 2026-09-24 19:31 UTCCISA KEV update
  7. 2026-09-24 16:01 UTCEG score recompute
  8. 2026-09-24 16:01 UTCGHSA enrichment
  9. 2026-09-24 14:00 UTCEPSS rescore
  10. 2026-09-24 11:58 UTCGHSA enrichment
  11. 2026-09-24 07:53 UTCGHSA enrichment
  12. 2026-09-24 03:49 UTCGHSA enrichment
  13. 2026-09-23 23:44 UTCGHSA enrichment
  14. 2026-09-23 19:40 UTCGHSA enrichment
  15. 2026-09-23 15:36 UTCEG score recompute
  16. 2026-09-23 15:36 UTCGHSA enrichment
  17. 2026-09-23 13:44 UTCEPSS rescore
  18. 2026-09-23 11:32 UTCGHSA enrichment
  19. 2026-09-23 07:29 UTCGHSA enrichment
  20. 2026-09-23 03:25 UTCGHSA enrichment
  21. 2026-09-22 23:21 UTCGHSA enrichment
  22. 2026-09-22 19:36 UTCCISA KEV update
  23. 2026-09-22 19:16 UTCGHSA enrichment
  24. 2026-09-22 15:12 UTCEG score recompute
  25. 2026-09-22 15:12 UTCGHSA enrichment
Show 75 more
  1. 2026-09-22 11:08 UTCGHSA enrichment
  2. 2026-09-22 07:04 UTCGHSA enrichment
  3. 2026-09-22 03:00 UTCGHSA enrichment
  4. 2026-09-21 22:57 UTCEG score recompute
  5. 2026-09-21 22:56 UTCGHSA enrichment
  6. 2026-09-21 20:28 UTCEPSS rescore
  7. 2026-09-21 19:09 UTCCISA KEV update
  8. 2026-09-21 18:52 UTCGHSA enrichment
  9. 2026-09-21 14:48 UTCGHSA enrichment
  10. 2026-09-21 10:41 UTCGHSA enrichment
  11. 2026-09-21 06:37 UTCGHSA enrichment
  12. 2026-09-21 02:33 UTCGHSA enrichment
  13. 2026-09-20 22:28 UTCEG score recompute
  14. 2026-09-20 22:28 UTCGHSA enrichment
  15. 2026-09-20 18:24 UTCGHSA enrichment
  16. 2026-09-20 14:20 UTCGHSA enrichment
  17. 2026-09-20 10:16 UTCGHSA enrichment
  18. 2026-09-20 06:13 UTCGHSA enrichment
  19. 2026-09-20 02:08 UTCGHSA enrichment
  20. 2026-09-19 22:04 UTCGHSA enrichment
  21. 2026-09-19 18:00 UTCEG score recompute
  22. 2026-09-19 18:00 UTCGHSA enrichment
  23. 2026-09-19 15:37 UTCEPSS rescore
  24. 2026-09-19 13:56 UTCGHSA enrichment
  25. 2026-09-19 09:51 UTCGHSA enrichment
  26. 2026-09-19 05:47 UTCGHSA enrichment
  27. 2026-09-19 01:43 UTCGHSA enrichment
  28. 2026-09-18 21:39 UTCEG score recompute
  29. 2026-09-18 21:39 UTCGHSA enrichment
  30. 2026-09-18 19:23 UTCEPSS rescore
  31. 2026-09-18 19:20 UTCCISA KEV update
  32. 2026-09-18 17:35 UTCGHSA enrichment
  33. 2026-09-18 14:15 UTCCISA KEV update
  34. 2026-09-18 13:31 UTCGHSA enrichment
  35. 2026-09-18 09:27 UTCGHSA enrichment
  36. 2026-09-18 05:23 UTCGHSA enrichment
  37. 2026-09-18 01:19 UTCGHSA enrichment
  38. 2026-09-17 21:15 UTCEG score recompute
  39. 2026-09-17 21:15 UTCGHSA enrichment
  40. 2026-09-17 19:23 UTCEPSS rescore
  41. 2026-09-17 19:23 UTCEPSS rescore
  42. 2026-09-17 17:11 UTCGHSA enrichment
  43. 2026-09-17 13:06 UTCGHSA enrichment
  44. 2026-09-17 09:02 UTCGHSA enrichment
  45. 2026-09-17 04:58 UTCGHSA enrichment
  46. 2026-09-17 00:54 UTCGHSA enrichment
  47. 2026-09-16 20:49 UTCGHSA enrichment
  48. 2026-09-16 16:44 UTCEG score recompute
  49. 2026-09-16 16:43 UTCGHSA enrichment
  50. 2026-09-16 14:10 UTCCISA KEV update
  51. 2026-09-16 14:05 UTCEPSS rescore
  52. 2026-09-16 12:36 UTCGHSA enrichment
  53. 2026-09-16 08:32 UTCEG score recompute
  54. 2026-09-16 08:32 UTCGHSA enrichment
  55. 2026-09-16 04:25 UTCGHSA enrichment
  56. 2026-09-16 00:21 UTCGHSA enrichment
  57. 2026-09-15 20:15 UTCGHSA enrichment
  58. 2026-09-15 16:11 UTCGHSA enrichment
  59. 2026-09-15 12:07 UTCGHSA enrichment
  60. 2026-09-15 08:03 UTCGHSA enrichment
  61. 2026-09-15 03:59 UTCGHSA enrichment
  62. 2026-09-14 23:53 UTCGHSA enrichment
  63. 2026-09-14 19:49 UTCGHSA enrichment
  64. 2026-09-14 19:24 UTCCISA KEV update
  65. 2026-09-14 15:45 UTCGHSA enrichment
  66. 2026-09-14 11:41 UTCGHSA enrichment
  67. 2026-09-14 07:38 UTCGHSA enrichment
  68. 2026-09-14 03:34 UTCGHSA enrichment
  69. 2026-09-13 23:30 UTCGHSA enrichment
  70. 2026-09-13 19:27 UTCGHSA enrichment
  71. 2026-09-13 15:23 UTCGHSA enrichment
  72. 2026-09-13 11:19 UTCGHSA enrichment
  73. 2026-09-13 07:15 UTCGHSA enrichment
  74. 2026-09-13 03:11 UTCGHSA enrichment
  75. 2026-09-12 23:08 UTCGHSA enrichment

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Frequently asked(6)

What is CVE-2021-26829?
CVE-2021-26829 is a critical 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

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