Is CVE-2021-33766 in the CISA KEV catalog?

Yes. CVE-2021-33766 is on the CISA Known Exploited Vulnerabilities list, added 2022-01-18.

What is the CVSS severity of CVE-2021-33766?

CVE-2021-33766 has a CVSS v3 base score of 7.3 (HIGH).

What is the EPSS score for CVE-2021-33766?

CVE-2021-33766 has an EPSS score of 97.50% (100th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-33766

HIGHCISA KEVEPSS 100th pctl

7.3

CVSS v3

NVD

Description

Microsoft Exchange Server Information Disclosure Vulnerability

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Exploit Intelligence

97.50%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Microsoft Exchange Server Information Disclosure

Microsoft Exchange Server contains an information disclosure vulnerability which can allow an unauthenticated attacker to steal email traffic from target.

Apply updates per vendor instructions.

Remediation due: 2022-02-01

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-29.