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CVE-2021-33766

Microsoft Exchange Server Information Disclosure Vulnerability

Actively exploited: CISA added it to its Known Exploited Vulnerabilities catalog on 18 Jan 2022.

Severity
High 7.3
Published
14 Jul 2021
Last changed
10 Aug 2026
Added to UpHeron
1 Nov 2026
Sources
NVD

Affected software

SoftwareAffected versions
Microsoft Exchange ServerServers and applications · cpe:a:microsoft:exchange_server
  • Version 2013-cumulative_update_23
  • Version 2016-cumulative_update_19
  • Version 2016-cumulative_update_20
  • Version 2019-cumulative_update_8
  • Version 2019-cumulative_update_9

Known exploited

CISA name
Microsoft Exchange Server Information Disclosure
Required action
Apply updates per vendor instructions.
Due for US agencies
1 Feb 2022
Used in ransomware
Not known

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2021-33766
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2021-33766