CVE-2026-55899

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-14. 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.

Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

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
38%
KEV
Not listed

Published

July 14, 2026

Last Modified

August 28, 2026

Advisory Details (1)

Auto-updated Jul 14, 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-2026-55899

Vendor Advisories for CVE-2026-55899(2)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 35× in last 7d / 169× 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 239 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55899?
CVE-2026-55899 is a high vulnerability published on July 14, 2026. Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
When was CVE-2026-55899 disclosed?
CVE-2026-55899 was first published in the National Vulnerability Database on July 14, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55899 actively exploited?
CVE-2026-55899 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 61.5% of all scored CVEs.
What is the CVSS score of CVE-2026-55899?
CVE-2026-55899 has a CVSS v4.0 base score of 7.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-55899?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55899, 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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