CVE-2026-45659

CRITICALPre-NVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-07-01), indicating real-world exploitation has been confirmed by US federal agencies. the CNA's CVSS baseline 8.8 retained for reference (NVD's own analysis pending). Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, cna:microsoft, epss, ghsa
Trending — 5 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 76%CVSS: 8.8Exploit: cisa kev · ssvc active · kev ransomware · epss top5pct · epss highExposed: 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 Office SharePoint allows an authorized attacker to execute code over a network.

CVSS v3
8.8
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

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
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
76%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

May 26, 2026

Last Modified

August 11, 2026

Advisory Details (1)

Auto-updated May 31, 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-2026-45659

Vendor Advisories for CVE-2026-45659(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 79× in last 7d / 368× 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 1,056 total refreshes for this CVE.

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

Frequently asked(6)

What is CVE-2026-45659?
CVE-2026-45659 is a critical vulnerability published on May 26, 2026. Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
When was CVE-2026-45659 disclosed?
CVE-2026-45659 was first published in the National Vulnerability Database on May 26, 2026, with the most recent update on August 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45659 actively exploited?
Yes. CISA added CVE-2026-45659 to the Known Exploited Vulnerabilities catalog on July 1, 2026, affecting Microsoft SharePoint Server. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-45659?
CVE-2026-45659 has a CVSS v4.0 base score of 8.8 (CNA self-assessment; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2026-45659?
CVE-2026-45659 affects Microsoft SharePoint Server. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2026-45659?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45659, 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.

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