CVE-2021-27065

CRITICALNVD 7.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 7.8 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: 100%CVSS: 7.8Exploit: cisa kev · ssvc active · kev ransomware · Metasploit · epss top5pct · epss high · public exploitExposed: 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
7.8
EG Score
9.0(high)
EG Risk
96(Act)
EG Risk 96/100SSVC: Act

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%
Automatability100% × 15%
Action: Fix now — active exploitation, automatable, high impact.
EPSS PROB
100%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

March 3, 2021

Last Modified

August 19, 2026

Advisory Details (4)

Auto-updated Jun 3, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: microsoft, cisa.
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-2021-27065
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-27065
generic

Packet Storm

http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
generic

Packet Storm

http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html

Vendor Advisories for CVE-2021-27065(1)

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.

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 100× in last 7d / 402× 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 1,526 total refreshes for this CVE.

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

Publicly available exploits

(3 references)

Working exploit code is in the public domain (1 Metasploit module) (1 GitHub PoC) (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-49637
    First seen Mar 11, 2021

    Microsoft Exchange 2019 - Server-Side Request Forgery (Proxylogon) (PoC)

    Open source ↗
  • GitHub PoCadamrpostjr/cve-2021-27065
    First seen Mar 6, 2021

    Quick One Line Powershell scripts to detect for webshells, possible zips, and logs.

    Open source ↗
  • Metasploitexploit/windows/http/exchange_proxylogon_rce✓ verified
    First seen Mar 2, 2021

    Microsoft Exchange ProxyLogon RCE

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-27065?
CVE-2021-27065 is a critical vulnerability published on March 3, 2021. Microsoft Exchange Server Remote Code Execution Vulnerability
When was CVE-2021-27065 disclosed?
CVE-2021-27065 was first published in the National Vulnerability Database on March 3, 2021, 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-2021-27065 actively exploited?
Yes. CISA added CVE-2021-27065 to the Known Exploited Vulnerabilities catalog on November 3, 2021, 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-2021-27065?
CVE-2021-27065 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-27065?
CVE-2021-27065 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-2021-27065?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27065, 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-2021-27065

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