KEV Entry

CVE-2021-26855

Known Exploited Vulnerability Entry Shadowserver

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Entry Details
Confirmed Exploited

CVE-2021-26855

2026-07-09 00:00 UTC

Characteristics

98.0

Timestamps

2023-10-13

2023-10-13

2026-07-09

Scope

Affected: Microsoft / Exchange | Class: email | Severity: Critical (CVSS 9.8) | IoT: no | In CISA KEV: yes | Honeypot connections on 2026-07-09: 423

References
  • {'id': 'CVE-2021-26855', 'url': 'https://www.cve.org/CVERecord?id=CVE-2021-26855'}
  • {'id': 'shadowserver', 'url': 'https://www.shadowserver.org/what-we-do/network-reporting/honeypot-exploited-vulnerabilities-report/'}

baf44e82-de07-4749-ae2b-3b12bf7c1f92

Shadowserver
c8fb6bf1-f81f-4cb8-95b1-eadbb3b54ee8

2026-06-30 09:22 UTC

2026-07-11 01:00 UTC

Evidence
1
Type Source Signal Confidence Details GCVE Metadata
honeypot shadowserver in_the_wild_attempts 0.70
View details 
{
  "1d": "17",
  "30d_avg": 12,
  "7d_avg": 15,
  "90d_avg": 8,
  "cisa_kev": "yes",
  "class": "email",
  "connections": 423,
  "feed": "Shadowserver Foundation honeypot/exploited-vulnerabilities",
  "iot": "no",
  "observation_date": "2026-07-09",
  "product": "Exchange",
  "type": "http-scan",
  "vendor": "Microsoft",
  "vulnerability_class": "CVSS",
  "vulnerability_score": 9.8,
  "vulnerability_severity": "Critical"
}
 -
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