Microsoft Exchange Server
YES - ON THE CISA KEV LIST
CVE-2021-33766
Microsoft Exchange Server Information Disclosure
overdue since 2022-02-01
Microsoft: 391 entries (22.0% of all KEV entries are from this vendor); 41 added in 2026.
BOD 26-04 note: this is the date printed in the CISA catalog. A federal agency's actual deadline is set by its SSVC tier - Act (3 days), Attend (14 days), Track (60 days), or the next scheduled upgrade - counted from the KEV listing date or the date the vulnerability is identified in its environment, whichever comes first. Use the tier helper on each CVE page for your own window.
Your BOD 26-04 window (SSVC tier helper)
Your remediation window ends:
Description
Microsoft Exchange Server contains an information disclosure vulnerability which can allow an unauthenticated attacker to steal email traffic from target.
Required action (CISA)
Apply updates per vendor instructions.
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-33766
References
Other KEV entries for this vendor: Microsoft
- CVE-2026-124194 - Office (2026-11-10)
- CVE-2026-96951 - Windows (2026-10-13)
- CVE-2026-65660 - SharePoint (2026-09-25)
- CVE-2026-81963 - Windows (2026-09-08)
- CVE-2026-85880 - Windows (2026-09-08)
- CVE-2019-1068 - SQL Server (2026-08-26)
- CVE-2026-33824 - Internet Key Exchange (IKE) Service Extensions (2026-08-18)
- CVE-2026-55040 - SharePoint (2026-08-18)
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