HIGHCVSS 7.8Actively exploited · CISA KEV since 2021-11-03Vulnerability
CVE-2021-26857
Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
Properties
- Euvd product
- Microsoft Exchange Server 2016 Cumulative Update 17, Microsoft Exchange Server 2010 Service Pack 3, Microsoft Exchange Server 2016 Cumulative Update 14, Microsoft Exchange Server 2016 Cumulative Update 13, Microsoft Exchange Server 2019 Cumulative Update 5, Microsoft Exchange Server 2016 Cumulative Update 9, Microsoft Exchange Server 2013 Cumulative Update 22, Microsoft Exchange Server 2019 Cumulative Update 1, Microsoft Exchange Server 2016 Cumulative Update 16, Microsoft Exchange Server 2019 Cumulative Update 7, Microsoft Exchange Server 2019 Cumulative Update 6, Microsoft Exchange Server 2016 Cumulative Update 18, Microsoft Exchange Server 2016 Cumulative Update 15, Microsoft Exchange Server 2013 Cumulative Update 21, Microsoft Exchange Server 2016 Cumulative Update 10, Microsoft Exchange Server 2016 Cumulative Update 12, Microsoft Exchange Server 2016 Cumulative Update 8, Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 8, Microsoft Exchange Server 2016 Cumulative Update 11, Microsoft Exchange Server 2013 Service Pack 1, Microsoft Exchange Server 2019 Cumulative Update 2, Microsoft Exchange Server 2019, Microsoft Exchange Server 2019 Cumulative Update 3, Microsoft Exchange Server 2016 Cumulative Update 19
- Vulnerability name
- Microsoft Exchange Server Remote Code Execution Vulnerability
- First seen
- 2026-08-19T16:30:15+00:00
- Cvss score
- 7.8
- Epss score
- 0.95762
- Last seen
- 2026-10-19T12:00:27+00:00
- Due date
- 2022-05-03
- Euvd assigner
- microsoft
- Retrieved at
- 2026-10-21T01:24:47+00:00
- Exploited euvd since
- 2021-11-03T00:00:00+00:00
- Src batch id
- epss_history-20261020T103617Z-728ddd
- Source url
- https://epss.empiricalsecurity.com/epss_scores-2026-10-19.csv.gz
- Date added
- 2021-11-03
- Euvd base score version
- 3.1
- Score
- 7.8
- Fetched at
- 2026-10-20T10:36:20+00:00
- Euvd vendor
- Microsoft
- Cvss vector
- CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- In Signal since
- initial import (Sep 2026)
- Euvd base score
- 7.8
Related Entities (32 · showing 26)
AFFECTS_PRODUCT (26 · showing 20)
MENTIONED_IN (3)
DESCRIBES (1)
HAS_WEAKNESS (1)
INVOLVES (1)
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