CVE-2021-26855

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Entry Details

CVE-2021-26855

Confirmed

Yes

2021-11-03 00:00 UTC

Timestamps

2021-11-03

2021-11-03

Scope

KEV entry: Microsoft Exchange Server Remote Code Execution Vulnerability | Affected: Microsoft / Exchange Server | Description: Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain. | Required action: Apply updates per vendor instructions. | Due date: 2022-05-03 | Known ransomware campaign use (KEV): Known | Notes (KEV): Reference CISA's ED 21-02 (https://www.cisa.gov/news-events/directives/ed-21-02-mitigate-microsoft-exchange-premises-product-vulnerabilities) for further guidance and requirements. Note: The due date for addressing this vulnerability aligns with the requirements outlined in ED 21-02. https://nvd.nist.gov/vuln/detail/CVE-2021-26855

References
  • {'id': 'CVE-2021-26855', 'url': 'https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-26855'}

a24818ce-a975-43a1-80b3-1a2e2e4cefaa

405284c2-e461-4670-8979-7fd2c9755a60

2026-02-02 13:26 UTC

2026-02-06 07:53 UTC

Evidence (1)
Type Source Signal Confidence Details GCVE Metadata
vendor_report cisa-kev successful_exploitation 0.80
View details 
{
  "cwes": [
    "CWE-918"
  ],
  "date_added": "2021-11-03",
  "due_date": "2022-05-03",
  "feed": "CISA Known Exploited Vulnerabilities Catalog",
  "knownRansomwareCampaignUse": "Known",
  "product": "Exchange Server",
  "vendorProject": "Microsoft",
  "vulnerabilityName": "Microsoft Exchange Server Remote Code Execution Vulnerability"
}
 -
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