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
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
100%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

March 3, 2021

Last Modified

December 18, 2025

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

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 58× in last 7d / 363× 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 758 total refreshes for this CVE.

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

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 vendor + 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 December 18, 2025. 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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