CVE-2026-81399

MEDIUMPre-NVD 5.55.5—
EchelonGraph scoreHIGH confidence

Score 5.5 from GitHub Security Advisory published 2026-09-08. the CNA's CVSS baseline 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
Trending — 4 sources updated this week
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

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

Buffer over-read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

CVSS v3
5.5
EG Score
5.5(high)
EG Risk
25(Track)
EG Risk 25/100SSVC: 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
Severity55% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

September 8, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 9, 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-2026-81399

Vendor Advisories for CVE-2026-81399(2)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 37× in last 7d / 74× 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.

  1. 2026-09-18 20:51 UTCEG score recompute
  2. 2026-09-18 20:51 UTCVendor advisory
  3. 2026-09-18 20:50 UTCGHSA enrichment
  4. 2026-09-18 19:28 UTCEPSS rescore
  5. 2026-09-18 14:01 UTCVendor advisory
  6. 2026-09-18 14:01 UTCGHSA enrichment
  7. 2026-09-17 23:24 UTCEG score recompute
  8. 2026-09-17 23:24 UTCVendor advisory
  9. 2026-09-17 23:24 UTCGHSA enrichment
  10. 2026-09-17 20:30 UTCEG score recompute
  11. 2026-09-17 20:30 UTCVendor advisory
  12. 2026-09-17 20:30 UTCGHSA enrichment
  13. 2026-09-17 20:05 UTCEG score recompute
  14. 2026-09-17 20:05 UTCVendor advisory
  15. 2026-09-17 20:05 UTCGHSA enrichment
  16. 2026-09-16 22:05 UTCEG score recompute
  17. 2026-09-16 22:05 UTCVendor advisory
  18. 2026-09-16 22:05 UTCGHSA enrichment
  19. 2026-09-16 14:08 UTCEPSS rescore
  20. 2026-09-16 05:15 UTCEPSS rescore
  21. 2026-09-15 22:51 UTCVendor advisory
  22. 2026-09-15 22:51 UTCGHSA enrichment
  23. 2026-09-15 17:46 UTCEG score recompute
  24. 2026-09-15 17:46 UTCVendor advisory
  25. 2026-09-15 17:46 UTCGHSA enrichment
Show 49 more
  1. 2026-09-15 03:12 UTCEPSS rescore
  2. 2026-09-15 03:12 UTCEPSS rescore
  3. 2026-09-14 23:03 UTCVendor advisory
  4. 2026-09-14 23:02 UTCGHSA enrichment
  5. 2026-09-14 17:33 UTCVendor advisory
  6. 2026-09-14 17:33 UTCGHSA enrichment
  7. 2026-09-14 03:11 UTCEG score recompute
  8. 2026-09-14 03:11 UTCVendor advisory
  9. 2026-09-14 03:11 UTCGHSA enrichment
  10. 2026-09-13 00:50 UTCEG score recompute
  11. 2026-09-13 00:50 UTCVendor advisory
  12. 2026-09-13 00:50 UTCGHSA enrichment
  13. 2026-09-11 22:28 UTCVendor advisory
  14. 2026-09-11 22:28 UTCGHSA enrichment
  15. 2026-09-11 19:57 UTCVendor advisory
  16. 2026-09-11 19:57 UTCGHSA enrichment
  17. 2026-09-11 16:56 UTCEG score recompute
  18. 2026-09-11 16:56 UTCVendor advisory
  19. 2026-09-11 16:56 UTCGHSA enrichment
  20. 2026-09-11 14:53 UTCEPSS rescore
  21. 2026-09-11 14:53 UTCEPSS rescore
  22. 2026-09-10 23:23 UTCEG score recompute
  23. 2026-09-10 23:23 UTCGHSA enrichment
  24. 2026-09-09 21:44 UTCVendor advisory
  25. 2026-09-09 21:43 UTCGHSA enrichment
  26. 2026-09-09 19:56 UTCEG score recompute
  27. 2026-09-09 19:56 UTCVendor advisory
  28. 2026-09-09 19:56 UTCGHSA enrichment
  29. 2026-09-09 15:31 UTCEG score recompute
  30. 2026-09-09 15:31 UTCVendor advisory
  31. 2026-09-09 15:31 UTCGHSA enrichment
  32. 2026-09-08 23:53 UTCEG score recompute
  33. 2026-09-08 23:53 UTCVendor advisory
  34. 2026-09-08 23:53 UTCGHSA enrichment
  35. 2026-09-08 20:38 UTCEG score recompute
  36. 2026-09-08 20:38 UTCGHSA enrichment
  37. 2026-09-08 20:15 UTCEG score recompute
  38. 2026-09-08 20:15 UTCGHSA enrichment
  39. 2026-09-08 19:37 UTCEG score recompute
  40. 2026-09-08 19:37 UTCGHSA enrichment
  41. 2026-09-08 18:50 UTCEG score recompute
  42. 2026-09-08 18:50 UTCVendor advisory
  43. 2026-09-08 18:50 UTCGHSA enrichment
  44. 2026-09-08 18:36 UTCEG score recompute
  45. 2026-09-08 18:36 UTCVendor advisory
  46. 2026-09-08 18:35 UTCGHSA enrichment
  47. 2026-09-08 17:33 UTCEG score recompute
  48. 2026-09-08 17:33 UTCVendor advisory
  49. 2026-09-08 17:25 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-81399?
CVE-2026-81399 is a medium vulnerability published on September 8, 2026. Buffer over-read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
When was CVE-2026-81399 disclosed?
CVE-2026-81399 was first published in the National Vulnerability Database on September 8, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81399 actively exploited?
CVE-2026-81399 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 67.7% of all scored CVEs.
What is the CVSS score of CVE-2026-81399?
CVE-2026-81399 has a CVSS v4.0 base score of 5.5 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-81399?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81399, 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-2026-81399

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