CVE-2021-34473
Detail
Description
Microsoft Exchange Server Remote Code Execution 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:H/A:H
CNA: Microsoft Corporation
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 2.0 Severity and Vector Strings:
Vector:
(AV:N/AC:L/Au:N/C:C/I:C/A:C)
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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 Remote Code Execution Vulnerability
11/03/2021
11/17/2021
Apply updates per vendor instructions.
Weakness Enumeration
CWE-ID
CWE Name
Source
CWE-918
Server-Side Request Forgery (SSRF)
NIST
CISA-ADP
Change History
15 change records found show changes
Modified Analysis by NIST 10/29/2025 12:46:45 PM
Action
Type
Old Value
New Value
Added
Reference Type
CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34473 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-2021-34473
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-2021-34473
CVE Modified by CISA-ADP 10/21/2025 3:19:08 PM
Action
Type
Old Value
New Value
Added
Reference
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34473
Modified Analysis by NIST 2/24/2025 10:47:45 AM
Action
Type
Old Value
New Value
CVE Modified by CISA-ADP 2/04/2025 11:15:33 AM
Action
Type
Old Value
New Value
Added
CWE
CWE-918
CVE Modified by CVE 11/21/2024 1:10:29 AM
Action
Type
Old Value
New Value
Added
Reference
http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html
Added
Reference
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473
Added
Reference
https://www.zerodayinitiative.com/advisories/ZDI-21-821/
Modified Analysis by NIST 7/26/2024 3:26:02 PM
Action
Type
Old Value
New Value
CVE Modified by Microsoft Corporation 5/14/2024 5:13:29 AM
Action
Type
Old Value
New Value
CVE Modified by Microsoft Corporation 12/28/2023 6:15:32 PM
Action
Type
Old Value
New Value
Changed
Description
Microsoft Exchange Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-31196, CVE-2021-31206.
Microsoft Exchange Server Remote Code Execution Vulnerability
Added
CVSS V3.1
Microsoft Corporation AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE Remap by NIST 7/12/2022 1:42:04 PM
Action
Type
Old Value
New Value
Changed
CWE
NVD-CWE-noinfo
CWE-918
Modified Analysis by NIST 9/21/2021 1:38:08 PM
Action
Type
Old Value
New Value
Changed
Reference Type
http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html No Types Assigned
http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html Exploit, Third Party Advisory, VDB Entry
Changed
Reference Type
https://www.zerodayinitiative.com/advisories/ZDI-21-821/ Third Party Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-821/ Third Party Advisory, VDB Entry
CVE Modified by Microsoft Corporation 8/20/2021 2:15:07 PM
Action
Type
Old Value
New Value
Added
Reference
http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html [No Types Assigned]
Initial Analysis by NIST 7/19/2021 11:35:37 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:H/A:H
Added
CVSS V2
NIST (AV:N/AC:L/Au:N/C:C/I:C/A:C)
Added
CWE
NIST NVD-CWE-noinfo
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-2021-34473 No Types Assigned
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473 Patch, Vendor Advisory
Changed
Reference Type
https://www.zerodayinitiative.com/advisories/ZDI-21-821/ No Types Assigned
https://www.zerodayinitiative.com/advisories/ZDI-21-821/ Third Party Advisory
CVE Modified by Microsoft Corporation 7/19/2021 6:15:08 AM
Action
Type
Old Value
New Value
Added
Reference
https://www.zerodayinitiative.com/advisories/ZDI-21-821/ [No Types Assigned]
Quick Info
CVE Dictionary Entry: CVE-2021-34473 NVD
Published Date: 07/14/2021 NVD
Last Modified: 10/29/2025
Source: Microsoft Corporation