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CVE-2021-41350: Microsoft Exchange Server Spoofing Vulnerability

• Severity: medium (CVSS 4.3 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-10-13 · updated 2026-06-17

Description

Microsoft Exchange Server Spoofing Vulnerability

Affected products

• Microsoft Exchange Server: 2016-cumulative_update_21, 2016-cumulative_update_22, 2019-cumulative_update_10, 2019-cumulative_update_11
• Microsoft Exchange Server 2016 Cumulative Update 21: from 15.01.0 before 15.01.2308.015 — fixed in 15.01.2308.015
• Microsoft Exchange Server 2016 Cumulative Update 22: from 15.0.0 before 15.01.2375.012 — fixed in 15.01.2375.012
• Microsoft Exchange Server 2019 Cumulative Update 10: from 15.02.0 before 15.02.0922.014 — fixed in 15.02.0922.014
• Microsoft Exchange Server 2019 Cumulative Update 11: from 15.02.0 before 15.02.0986.009 — fixed in 15.02.0986.009

How to fix

Upgrade to a fixed version: Microsoft Exchange Server 2016 Cumulative Update 21 15.01.2308.015; Microsoft Exchange Server 2016 Cumulative Update 22 15.01.2375.012; Microsoft Exchange Server 2019 Cumulative Update 10 15.02.0922.014; Microsoft Exchange Server 2019 Cumulative Update 11 15.02.0986.009. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-41350
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-41350

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