CVE-2026-66808

HIGHPre-NVD 8.88.8—
EchelonGraph scoreHIGH confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-08-11. the CNA's CVSS baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
Trending — 4 sources updated this week
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 8.8Exploit: None knownExposed: 0

A fix is available — apply it.

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

CVSS v3
8.8
EG Score
8.8(high)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation2% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
78%
KEV
Not listed

Published

August 11, 2026

Last Modified

August 20, 2026

Advisory Details (1)

Auto-updated Aug 11, 2026
Patch available. Sources: microsoft.
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-2026-66808

Vendor Advisories for CVE-2026-66808(4)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatmulticluster-engine/hypershift-addon-rhel9-operator:17865483812026-08-12redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 88× in last 7d / 137× 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 137 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-66808?
CVE-2026-66808 is a high vulnerability published on August 11, 2026. Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
When was CVE-2026-66808 disclosed?
CVE-2026-66808 was first published in the National Vulnerability Database on August 11, 2026, with the most recent update on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66808 actively exploited?
CVE-2026-66808 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 21.9% of all scored CVEs.
What is the CVSS score of CVE-2026-66808?
CVE-2026-66808 has a CVSS v4.0 base score of 8.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-66808?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66808, 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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