CVE-2026-64909

HIGHPre-NVD 7.87.8—
EchelonGraph scoreHIGH confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-08-11. the CNA's CVSS baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, 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.

Integer underflow (wrap or wraparound) in Microsoft Office allows an unauthorized attacker to execute code locally.

CVSS v3
7.8
EG Score
7.8(high)
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
27%
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-2026-64909

Vendor Advisories for CVE-2026-64909(2)

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

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 84× in last 7d / 125× 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 125 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-64909?
CVE-2026-64909 is a high vulnerability published on August 11, 2026. Integer underflow (wrap or wraparound) in Microsoft Office allows an unauthorized attacker to execute code locally.
When was CVE-2026-64909 disclosed?
CVE-2026-64909 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-2026-64909 actively exploited?
CVE-2026-64909 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 72.8% of all scored CVEs.
What is the CVSS score of CVE-2026-64909?
CVE-2026-64909 has a CVSS v4.0 base score of 7.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-64909?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64909, 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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