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

August 19, 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 106× in last 7d / 447× 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 1,491 total refreshes for this CVE.

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

Explore the affected products and dependency analysis for CVE-2023-21529

Explore →

Is Your Infrastructure Affected by CVE-2023-21529?

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

Start Free Scan →Browse All CVEs