CVE-2026-8863

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-06-09. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

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

Multiple Microsoft-sigend UEFI SHIM bootloaders are vulnerable to SecureBoot bypass. An attacker with administrative privileges or the ability to modify the boot process could use one of the vulnerable shim bootloaders to bypass Secure Boot protections and execute arbitrary code before the operating system loads. Specific UEFI DBX update is required to block these vulnerable boot loaders.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: Track

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%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
1%
KEV
Not listed

Published

June 9, 2026

Last Modified

July 23, 2026

Advisory Details (3)

Auto-updated Jun 9, 2026
Patch available. Sources: cert, microsoft.
cert

VU#616257 - Microsoft-signed UEFI shim bootloaders vulnerable to Secure Boot bypass

https://www.kb.cert.org/vuls/id/616257
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-8863
cert

VU#616257 - Microsoft-signed UEFI shim bootloaders vulnerable to Secure Boot bypass

https://kb.cert.org/vuls/id/616257

Vendor Advisories for CVE-2026-8863(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Data Freshness Timeline

(refreshed 8× in last 7d / 51× 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 330 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-8863?
CVE-2026-8863 is a high vulnerability published on June 9, 2026. Multiple Microsoft-sigend UEFI SHIM bootloaders are vulnerable to SecureBoot bypass. An attacker with administrative privileges or the ability to modify the boot process could use one of the vulnerable shim bootloaders to bypass Secure Boot protections and execute arbitrary code before the…
When was CVE-2026-8863 disclosed?
CVE-2026-8863 was first published in the National Vulnerability Database on June 9, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8863 actively exploited?
CVE-2026-8863 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 98.6% of all scored CVEs.
What is the CVSS score of CVE-2026-8863?
CVE-2026-8863 has a CVSS v3.1 base score of 7.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-8863?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8863, 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-2026-8863

Explore →

Is Your Infrastructure Affected by CVE-2026-8863?

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

Start Free Scan →Browse All CVEs