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. a secondary CVSS source baseline 8.8 retained for reference (NVD's own analysis pending). Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, secondary
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: 9%CVSS: 8.8Exploit: cisa kevExposed: 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
9%
EPSS %ILE
95%
KEV
⚠ Exploited

Published

May 26, 2026

Last Modified

July 23, 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 62× in last 7d / 331× 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 461 total refreshes for this CVE.

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

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 July 23, 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 v3 base score of 8.8 (NVD). 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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