Microsoft Exchange Server Information Disclosure

HIGH 7.3EXPLOITED (CISA KEV)CVE-2021-33766 · Published 14/07/2021 · updated 10/08/2026

Microsoft Exchange Server Information Disclosure. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 18/01/2022. Patch affected systems as an emergency.

Package	Affected versions	Patched versions
exchange server microsoft	`= 2013= 2016= 2019`	No fix yet

Description

Microsoft Exchange Server Information Disclosure Vulnerability

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766 · Patch
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766 · Patch
zerodayinitiative.com/advisories/ZDI-21-798 · Third Party Advisory
cisa.gov/known-exploited-vulnerabilities-catalog · US Government Resource
CISA KEV · CVE-2021-33766

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