CVE-2021-41349
MediumExploitedMicrosoft Exchange Server Spoofing Vulnerability
Published Nov 9, 2021 · Updated Aug 19, 2026
Key Facts
Patch immediately- CVE-2021-41349 is a medium-severity vulnerability (CVSS 6.5 v3.1) affecting Exchange Server (Microsoft), Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Exchange Server 2016 Cumulative Update 21 and 3 more products.
- It is exploited in the wild, listed in Industry KEV feed since May 31, 2022. No public exploit code is known.
- EPSS estimates a 93% probability of exploitation in the next 30 days.
- Fixed versions are available, including Exchange Server 15.00.1497.026, Exchange Server 15.01.2308.020, Exchange Server 15.01.2375.017.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS (30-day exploit likelihood)
93%
Higher than 99.8% of all scored CVEs
Exploited in the wild
Yes
1 catalog listing
Public exploit code
None known
Get the full CVE-2021-41349 brief as a PDF
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Description
Microsoft Exchange Server Spoofing Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | May 31, 2022 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
15 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Exchange ServerMicrosoft | 2013-cumulative_update_23, 2016-cumulative_update_21, 2016-cumulative_update_22, 2019-cumulative_update_10, 2019-cumulative_update_11 | 15.00.1497.026 |
| Microsoft Exchange Server 2013 Cumulative Update 23 | >= 15.00.0 | 15.00.1497.026 |
| Microsoft Exchange Server 2016 Cumulative Update 21 | >= 15.01.0 | 15.01.2308.020 |
| Microsoft Exchange Server 2016 Cumulative Update 22 | >= 15.0.0 | 15.01.2375.017 |
| Microsoft Exchange Server 2019 Cumulative Update 10 | >= 15.02.0 | 15.02.0792.019 |
Patched Releases
Exchange Server
15.00.1497.026, 15.01.2308.020, 15.01.2375.017, 15.02.0792.019, 15.02.0986.014
Microsoft Exchange Server 2013 Cumulative Update 23
15.00.1497.026
Microsoft Exchange Server 2016 Cumulative Update 21
15.01.2308.020
Microsoft Exchange Server 2016 Cumulative Update 22
15.01.2375.017
Microsoft Exchange Server 2019 Cumulative Update 10
15.02.0792.019
Microsoft Exchange Server 2019 Cumulative Update 11
15.02.0986.014
Timeline
Publicly disclosed
Nov 9, 2021
Added to Industry KEV feed
May 31, 2022
Last updated
Aug 19, 2026
References
FAQ
Common Questions.
Microsoft Exchange Server Spoofing Vulnerability
Affected: Exchange Server (Microsoft) versions 2013-cumulative_update_23, 2016-cumulative_update_21, 2016-cumulative_update_22, 2019-cumulative_update_10, 2019-cumulative_update_11; Microsoft Exchange Server 2013 Cumulative Update 23 versions >= 15.00.0; Microsoft Exchange Server 2016 Cumulative Update 21 versions >= 15.01.0, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since May 31, 2022.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Exchange Server 15.00.1497.026, Exchange Server 15.01.2308.020, Exchange Server 15.01.2375.017.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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