CVE-2021-3418

MEDIUMNVD 6.46.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.4 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 62% of all CVEs by exploit prediction. 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
Trending — 3 sources updated this week
6.4
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.4Exploit: NoneExposed: 0

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

If certificates that signed grub are installed into db, grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown, yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism.

CVSS v3
6.4
EG Score
6.4(medium)
EPSS
37.7%
KEV
Not listed

Published

March 15, 2021

Last Modified

November 21, 2024

References (2)

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 12× in last 7d / 50× 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 105 total refreshes for this CVE.

  1. 2026-07-22 22:48 UTCEG score recompute
  2. 2026-07-22 14:06 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
  5. 2026-07-20 17:05 UTCEPSS rescore
  6. 2026-07-19 14:29 UTCEPSS rescore
  7. 2026-07-19 02:27 UTCEPSS rescore
  8. 2026-07-18 23:59 UTCOSV refresh
  9. 2026-07-18 10:02 UTCEPSS rescore
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  11. 2026-07-16 17:00 UTCEPSS rescore
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  20. 2026-07-12 05:44 UTCEPSS rescore
  21. 2026-07-11 08:25 UTCEPSS rescore
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  23. 2026-07-09 19:07 UTCEPSS rescore
  24. 2026-07-08 15:12 UTCEPSS rescore
  25. 2026-07-07 13:43 UTCEPSS rescore
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  1. 2026-07-06 16:25 UTCEPSS rescore
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  3. 2026-07-06 02:21 UTCEPSS rescore
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  5. 2026-07-05 02:28 UTCEPSS rescore
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  9. 2026-07-02 16:57 UTCEPSS rescore
  10. 2026-07-01 15:04 UTCEPSS rescore
  11. 2026-07-01 06:48 UTCOSV refresh
  12. 2026-06-30 23:20 UTCEPSS rescore
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  20. 2026-06-25 13:48 UTCEPSS rescore
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  22. 2026-06-24 14:03 UTCEPSS rescore
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  24. 2026-06-23 21:31 UTCEPSS rescore
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  26. 2026-06-22 14:24 UTCEPSS rescore
  27. 2026-06-21 14:55 UTCEPSS rescore
  28. 2026-06-21 01:58 UTCEPSS rescore
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  30. 2026-06-19 19:24 UTCEPSS rescore
  31. 2026-06-19 19:24 UTCEPSS rescore
  32. 2026-06-18 17:51 UTCEPSS rescore
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  39. 2026-06-15 17:46 UTCEPSS rescore
  40. 2026-06-14 23:15 UTCEPSS rescore
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  42. 2026-06-13 22:58 UTCEPSS rescore
  43. 2026-06-13 22:58 UTCEPSS rescore
  44. 2026-06-13 11:43 UTCOSV refresh
  45. 2026-06-12 23:10 UTCEPSS rescore
  46. 2026-06-11 13:58 UTCEPSS rescore
  47. 2026-06-11 13:58 UTCEPSS rescore
  48. 2026-06-10 22:16 UTCEPSS rescore
  49. 2026-06-10 22:16 UTCEPSS rescore
  50. 2026-06-10 13:20 UTCEPSS rescore
  51. 2026-06-08 14:15 UTCEPSS rescore
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  53. 2026-06-07 15:23 UTCEPSS rescore
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  55. 2026-06-06 13:46 UTCEPSS rescore
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  57. 2026-06-05 22:45 UTCEPSS rescore
  58. 2026-06-05 06:09 UTCEPSS rescore
  59. 2026-06-05 06:09 UTCEPSS rescore
  60. 2026-06-04 13:10 UTCEPSS rescore
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  62. 2026-06-02 20:11 UTCEPSS rescore
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  64. 2026-06-01 13:50 UTCEPSS rescore
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  66. 2026-05-31 22:29 UTCEPSS rescore
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  68. 2026-05-29 13:42 UTCEPSS rescore
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  71. 2026-05-27 13:39 UTCEPSS rescore
  72. 2026-05-27 13:39 UTCEPSS rescore
  73. 2026-05-26 19:44 UTCEG score recompute
  74. 2026-05-26 19:44 UTCVendor advisory
  75. 2026-05-26 19:44 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-3418?
CVE-2021-3418 is a medium vulnerability published on March 15, 2021. If certificates that signed grub are installed into db, grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown, yet it could have been tampered. This flaw is a reintroduction…
When was CVE-2021-3418 disclosed?
CVE-2021-3418 was first published in the National Vulnerability Database on March 15, 2021, 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-2021-3418 actively exploited?
CVE-2021-3418 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-3418?
CVE-2021-3418 has a CVSS v3 base score of 6.4 (NVD).
How do I remediate CVE-2021-3418?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3418, 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.

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