CVE-2026-55009

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: 3%CVSS: 7.8Exploit: None knownExposed: 0

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

Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
36(Track)
EG Risk 36/100SSVC: 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%
Exploitation3% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
3%
EPSS %ILE
84%
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-2026-55009

Vendor Advisories for CVE-2026-55009(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 34× in last 7d / 172× 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 243 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55009?
CVE-2026-55009 is a high vulnerability published on July 14, 2026. Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.
When was CVE-2026-55009 disclosed?
CVE-2026-55009 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-2026-55009 actively exploited?
CVE-2026-55009 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3% probability of exploitation in the next 30 days, which ranks it in the top 16.4% of all scored CVEs.
What is the CVSS score of CVE-2026-55009?
CVE-2026-55009 has a CVSS v4.0 base score of 7.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-55009?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55009, 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-2026-55009

Explore →

Is Your Infrastructure Affected by CVE-2026-55009?

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

Start Free Scan →Browse All CVEs