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CVE-2021-33766

Microsoft Exchange Server Information Disclosure Vulnerability

CVSS 3.1 High 7.3Known exploited (CISA KEV)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C

Description

Microsoft Exchange Server Information Disclosure Vulnerability

Official description from the CVE record, published by microsoft. Copyright © 1999-2026 The MITRE Corporation. See /security/cve/legal for the CVE license. View the record on cve.org

Key data

CVSS 3.1 High 7.3

Score published by microsoft in the CVE record.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C

  • Attack vector: Network

    The vulnerable component can be reached over a network, possibly from the Internet.

  • Attack complexity: Low

    No special conditions are needed. The attack can be repeated at will.

  • Privileges required: None

    No account or privileges are needed.

  • User interaction: None

    No action from any user is needed.

  • Scope: Unchanged

    The impact stays within the vulnerable component.

  • Confidentiality impact: Low

    Limited effect on the secrecy of data.

  • Integrity impact: Low

    Limited effect on the trustworthiness of data.

  • Availability impact: Low

    Limited effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.
Score
0.98176 (98.2% probability)
Percentile
99.9%
Scores of
Nov 10, 2026
Model
v2026.06.15

CISA Known Exploited Vulnerabilities

This CVE is listed in the CISA KEV catalog.
Name in the catalog
Microsoft Exchange Server Information Disclosure
Added to the catalog
Jan 18, 2022
Federal due date
Feb 1, 2022

CISA assessment as of Feb 4, 2025

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.
Exploitation
Recorded by CISA as active
Automatable
yes
Technical impact
partial

Affected products

Products listed in the CVE record, as the CNA published them.

  • Microsoft Exchange Server 2013 Cumulative Update 23

    • affected: 15.00.0 up to before 15.00.1497.015

  • Microsoft Exchange Server 2016 Cumulative Update 19

    • affected: 15.01.0 up to before 15.01.2176.012

  • Microsoft Exchange Server 2016 Cumulative Update 20

    • affected: 15.01.0 up to before 15.01.2242.008

  • Microsoft Exchange Server 2019 Cumulative Update 8

    • affected: 15.02.0 up to before 15.02.0792.013

  • Microsoft Exchange Server 2019 Cumulative Update 9

    • affected: 15.02.0 up to before 15.02.0858.010

References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

Timeline

  1. ID reserved
  2. Record published
  3. Added to CISA KEV
  4. Record last updated

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:51 UTC. Sources and licenses