CVE-2021-27104

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 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
9.8EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 57%CVSS: 9.8Exploit: cisa kev · ssvc active · kev ransomware · epss top5pct · epss highExposed: 0

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

Accellion FTA 9_12_370 and earlier is affected by OS command execution via a crafted POST request to various admin endpoints. The fixed version is FTA_9_12_380 and later.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
84(Attend)
EG Risk 84/100SSVC: 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
Severity98% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
57%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

February 16, 2021

Last Modified

November 3, 2025

Advisory Details (1)

Auto-updated Sep 24, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
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-2021-27104

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 60× in last 7d / 258× 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 972 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-27104?
CVE-2021-27104 is a critical vulnerability published on February 16, 2021. Accellion FTA 912370 and earlier is affected by OS command execution via a crafted POST request to various admin endpoints. The fixed version is FTA912_380 and later.
When was CVE-2021-27104 disclosed?
CVE-2021-27104 was first published in the National Vulnerability Database on February 16, 2021, with the most recent update on November 3, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-27104 actively exploited?
Yes. CISA added CVE-2021-27104 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Accellion FTA. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-27104?
CVE-2021-27104 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2021-27104?
CVE-2021-27104 affects Accellion FTA. 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-2021-27104?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27104, 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

Explore the affected products and dependency analysis for CVE-2021-27104

Explore →

Is Your Infrastructure Affected by CVE-2021-27104?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs