CVE-2020-3455

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.8 under NVD CVSS v3. EPSS exploit probability: 0.3% (25th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.8EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.8Exploit: None knownExposed services: Not assessed

A fix is referenced (a reference tagged "Patch", often a source commit), but no release containing it is confirmed — find the release that contains it; until it is applied, mitigate (WAF / firewall / segmentation).

A vulnerability in the secure boot process of Cisco FXOS Software could allow an authenticated, local attacker to bypass the secure boot mechanisms. The vulnerability is due to insufficient protections of the secure boot process. An attacker could exploit this vulnerability by injecting code into a specific file that is then referenced during the device boot process. A successful exploit could allow the attacker to break the chain of trust and inject code into the boot process of the device which would be executed at each boot and maintain persistence across reboots.

CVSS v3
7.8
EG Score
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100CISA SSVC

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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines; until then, restrict network exposure of the affected system or apply the vendor's mitigation.
EPSS PROB
0.3%
EPSS %ILE
26th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines; until then, restrict network exposure of the affected system or apply the vendor's mitigation.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 21, 2020

Last Modified

November 21, 2024

Advisory Details (1)

Auto-updated Sep 24, 2026
Fix referenced — no release confirmed yet.
generic

Cisco FXOS Software for Firepower 4100/9300 Series Appliances Secure Boot Bypass Vulnerability

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fxos-sbbp-XTuPkYTn

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 25× 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 153 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2020-3455?
CVE-2020-3455 is a high vulnerability published on October 21, 2020. A vulnerability in the secure boot process of Cisco FXOS Software could allow an authenticated, local attacker to bypass the secure boot mechanisms. The vulnerability is due to insufficient protections of the secure boot process. An attacker could exploit this vulnerability by injecting code into a…
When was CVE-2020-3455 disclosed?
CVE-2020-3455 was first published on October 21, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-3455 actively exploited?
CVE-2020-3455 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2020-3455?
CVE-2020-3455 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2020-3455?
A fix for CVE-2020-3455 is referenced (a reference tagged "Patch", often a source commit), but EchelonGraph has no release containing it on record. Check that reference and the vendor's advisory for a release that contains the fix and update to it; until then, restrict network exposure of the affected system or apply the vendor's mitigation.

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