CVE-2023-21529

CRITICALNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-04-13), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
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: 62%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.

Microsoft Exchange Server Remote Code Execution Vulnerability

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
62%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

February 14, 2023

Last Modified

April 14, 2026

Advisory Details (3)

Auto-updated May 19, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: microsoft, cisa.
generic

Storm-1175 focuses gaze on vulnerable web-facing assets in high-tempo Medusa ransomware operations | Microsoft Security Blog

https://www.microsoft.com/en-us/security/blog/2026/04/06/storm-1175-focuses-gaze-on-vulnerable-web-facing-assets-in-high-tempo-medusa-ransomware-operations/
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529
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-2023-21529

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 71× in last 7d / 393× 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 871 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2023-21529?
CVE-2023-21529 is a critical vulnerability published on February 14, 2023. Microsoft Exchange Server Remote Code Execution Vulnerability
When was CVE-2023-21529 disclosed?
CVE-2023-21529 was first published in the National Vulnerability Database on February 14, 2023, with the most recent update on April 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-21529 actively exploited?
Yes. CISA added CVE-2023-21529 to the Known Exploited Vulnerabilities catalog on April 13, 2026, affecting Microsoft Exchange Server. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2023-21529?
CVE-2023-21529 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-2023-21529?
CVE-2023-21529 affects Microsoft Exchange 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-2023-21529?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-21529, 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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