CVE-2021-33766
mediumpriority · act · 90OT risk · criticalKEV · exploitedEPSS 0.982 · 100 %ileexploit · PoCDEEURUUSadded 2022-01-18remediate by 2022-02-01
required action Apply updates per vendor instructions.
EPSS · scored 2026-10-27
Microsoft Exchange Server Information Disclosure
Microsoft Exchange Server Information Disclosure Vulnerability
remediations
Vendor fix, mitigation, or workaround guidance, as published by each source.
A vendor fix is available.
- FixedMicrosoft Exchange Server 2013 Cumulative Update 23msrc_csaf
15.00.1497.015:Security Update:https://support.microsoft.com/help/5001779
https://support.microsoft.com/help/5001779 - FixedMicrosoft Exchange Server 2016 Cumulative Update 19msrc_csaf
15.01.2176.012:Security Update:https://support.microsoft.com/help/5001779
https://support.microsoft.com/help/5001779 - FixedMicrosoft Exchange Server 2016 Cumulative Update 20msrc_csaf
15.01.2242.008:Security Update:https://support.microsoft.com/help/5001779
https://support.microsoft.com/help/5001779 - FixedMicrosoft Exchange Server 2019 Cumulative Update 8msrc_csaf
15.02.0792.013:Security Update:https://support.microsoft.com/help/5001779
https://support.microsoft.com/help/5001779 - FixedMicrosoft Exchange Server 2019 Cumulative Update 9msrc_csaf
15.02.0858.010:Security Update:https://support.microsoft.com/help/5001779
https://support.microsoft.com/help/5001779
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
exploits (2)
Public proof-of-concept and weaponised exploit code.
affected products (28)
Products and version ranges known to be affected.
- Microsoft Exchange Server 2013 Cumulative Update 23all versionscert_bundDEcpe:/a:microsoft:exchange_server_2013::cumulative_update_23
- Microsoft Exchange Server 2016 Cumulative Update 19all versionscert_bundDEcpe:/a:microsoft:exchange_server_2016:cumulative_update_19
- Microsoft Exchange Server 2016 Cumulative Update 20all versionscert_bundDEcpe:/a:microsoft:exchange_server_2016:cumulative_update_20
- Microsoft Exchange Server 2019 Cumulative Update 8all versionscert_bundDEcpe:/a:microsoft:exchange_server_2019:cumulative_update_8
- Microsoft Exchange Server 2019 Cumulative Update 9all versionscert_bundDEcpe:/a:microsoft:exchange_server_2019:cumulative_update_9
advisories (2)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2024-1897Microsoft Exchange Server: Mehrere SchwachstellenDeutsch2021-07-13csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Microsoft Exchange Server 2013, Microsoft Exchange Server 2016 und Microsoft Exchange Server 2019 ausnutzen, um beliebigen Programmcode auszuführen, um seine Privilegien zu erhöhen und um Informationen offenzulegen.
- msrc_CVE-2021-33766Microsoft Exchange Server Information Disclosure Vulnerability2021-07-13csaf · msrc_csafUS
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
also known as (4)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (10)
External citations — patches, advisories, analysis.
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766cnnvd
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766cnnvd
- https://vigilance.fr/vulnerability/Microsoft-Exchange-Server-vulnerabilities-of-July-2021-35886cnnvd
- https://www.cybersecurity-help.cz/vdb/SB2021071342cnnvd
- https://www.zerodayinitiative.com/advisories/ZDI-21-798/cnnvd
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766enisa_euvd
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766PatchVendor Advisorynvd
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766PatchVendor Advisorynvd
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