CVE-2021-33766
Detail
Description
Microsoft Exchange Server Information Disclosure Vulnerability
Metrics
CVSS Version 4.0
CVSS Version 3.x
CVSS Version 2.0
NVD enrichment efforts reference publicly available information to associate
vector strings. CVSS information contributed by other sources is also
displayed.
CVSS 4.0 Severity and Vector Strings:
NVD assessment
not yet provided.
CVSS 3.x Severity and Vector Strings:
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA: Microsoft Corporation
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
CVSS 2.0 Severity and Vector Strings:
Vector:
(AV:N/AC:L/Au:N/C:P/I:N/A:N)
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This CVE is in CISA's Known Exploited Vulnerabilities Catalog
Reference
CISA's BOD 22-01 and Known
Exploited Vulnerabilities Catalog for further guidance and requirements.
Vulnerability Name
Date Added
Due Date
Required Action
Microsoft Exchange Server Information Disclosure
01/18/2022
02/01/2022
Apply updates per vendor instructions.
Weakness Enumeration
CWE-ID
CWE Name
Source
NVD-CWE-noinfo
Insufficient Information
NIST
Change History
15 change records found show changes
Modified Analysis by NIST
8/10/2026 3:58:44 PM
Action
Type
Old Value
New Value
Added
Reference Type
Microsoft Corporation: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766 Types: Patch, Vendor Advisory
CVE Modified by Microsoft Corporation
8/10/2026 12:17:40 PM
Action
Type
Old Value
New Value
Added
Reference
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766
Removed
Reference
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766
Removed
Reference
https://www.zerodayinitiative.com/advisories/ZDI-21-798/
Removed
Reference Type
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766 Types: Patch, Vendor Advisory
Removed
Reference Type
https://www.zerodayinitiative.com/advisories/ZDI-21-798/ Types: Third Party Advisory, VDB Entry
Changed
Affected
[{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 9","cpes":["cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_9:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.02.0","lessThan":"15.02.0858.010","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 20","cpes":["cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_20:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.01.0","lessThan":"15.01.2242.008","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2013 Cumulative Update 23","cpes":["cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.00.0","lessThan":"15.00.1497.015","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 19","cpes":["cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.01.0","lessThan":"15.01.2176.012","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 8","cpes":["cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.02.0","lessThan":"15.02.0792.013","versionType":"custom","status":"affected"}]}]
[{"vendor":"Microsoft","product":"Microsoft Exchange Server 2013 Cumulative Update 23","platforms":["x64-based Systems"],"versions":[{"version":"15.00.0","lessThan":"15.00.1497.015","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 19","platforms":["x64-based Systems"],"versions":[{"version":"15.01.0","lessThan":"15.01.2176.012","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 20","platforms":["x64-based Systems"],"versions":[{"version":"15.01.0","lessThan":"15.01.2242.008","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 8","platforms":["x64-based Systems"],"versions":[{"version":"15.02.0","lessThan":"15.02.0792.013","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 9","platforms":["x64-based Systems"],"versions":[{"version":"15.02.0","lessThan":"15.02.0858.010","versionType":"custom","status":"affected"}]}]
CVE Modified by CISA-ADP
6/16/2026 11:55:11 PM
Action
Type
Old Value
New Value
Added
SSVC
{"timestamp":"2025-02-04T19:07:59.976278Z","id":"CVE-2021-33766","options":[{"exploitation":"active"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}
CVE Modified by Microsoft Corporation
6/16/2026 11:55:11 PM
Action
Type
Old Value
New Value
Added
Affected
[{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 9","cpes":["cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_9:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.02.0","lessThan":"15.02.0858.010","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 20","cpes":["cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_20:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.01.0","lessThan":"15.01.2242.008","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2013 Cumulative Update 23","cpes":["cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.00.0","lessThan":"15.00.1497.015","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 19","cpes":["cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.01.0","lessThan":"15.01.2176.012","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 8","cpes":["cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*"],"platforms":["x64-based Systems"],"versions":[{"version":"15.02.0","lessThan":"15.02.0792.013","versionType":"custom","status":"affected"}]}]
Modified Analysis by NIST
10/29/2025 12:47:15 PM
Action
Type
Old Value
New Value
Added
Reference Type
CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766 Types: US Government Resource
CVE Modified by CISA-ADP
10/21/2025 8:17:37 PM
Action
Type
Old Value
New Value
Added
Reference
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766
CVE Modified by CISA-ADP
10/21/2025 4:18:37 PM
Action
Type
Old Value
New Value
Removed
Reference
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766
CVE Modified by CISA-ADP
10/21/2025 3:19:07 PM
Action
Type
Old Value
New Value
Added
Reference
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766
Modified Analysis by NIST
3/07/2025 5:01:06 PM
Action
Type
Old Value
New Value
Added
CWE
NVD-CWE-noinfo
Removed
CWE
CWE-287
CVE Modified by CVE
11/21/2024 1:09:32 AM
Action
Type
Old Value
New Value
Added
Reference
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766
Added
Reference
https://www.zerodayinitiative.com/advisories/ZDI-21-798/
Modified Analysis by NIST
7/24/2024 12:45:35 PM
Action
Type
Old Value
New Value
CVE Modified by Microsoft Corporation
5/14/2024 5:11:39 AM
Action
Type
Old Value
New Value
CVE Modified by Microsoft Corporation
12/28/2023 6:15:20 PM
Action
Type
Old Value
New Value
Changed
Description
Microsoft Exchange Information Disclosure Vulnerability
Microsoft Exchange Server Information Disclosure Vulnerability
Added
CVSS V3.1
Microsoft Corporation AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Initial Analysis by NIST
7/16/2021 10:41:29 AM
Action
Type
Old Value
New Value
Added
CVSS V3.1
NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Added
CVSS V2
NIST (AV:N/AC:L/Au:N/C:P/I:N/A:N)
Added
CWE
NIST CWE-287
Added
CPE Configuration
OR
*cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
*cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*
*cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_20:*:*:*:*:*:*
*cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*
*cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_9:*:*:*:*:*:*
Changed
Reference Type
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766 No Types Assigned
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766 Patch, Vendor Advisory
Changed
Reference Type
https://www.zerodayinitiative.com/advisories/ZDI-21-798/ No Types Assigned
https://www.zerodayinitiative.com/advisories/ZDI-21-798/ Third Party Advisory, VDB Entry
CVE Modified by Microsoft Corporation
7/15/2021 3:15:08 AM
Action
Type
Old Value
New Value
Added
Reference
https://www.zerodayinitiative.com/advisories/ZDI-21-798/ [No Types Assigned]
Quick Info
CVE Dictionary Entry: CVE-2021-33766 NVD
Published Date: 07/14/2021 NVD
Last Modified: 08/10/2026
Source: Microsoft Corporation
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