CVE-2026-21511
Microsoft Outlook Spoofing Vulnerability
CVSS Score
7.5
EPSS Score
0.2%
EPSS Percentile
46th
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
| Vendor | microsoft |
| Product | microsoft 365 apps for enterprise |
| Ecosystems | |
| Industries | TechnologyEnterprise |
| Published | Feb 10, 2026 |
| Last Updated | Apr 10, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Affected Versions
Microsoft / Microsoft 365 Apps for Enterprise
16.0.1 < https://aka.ms/OfficeSecurityReleases
Microsoft / Microsoft Office 2019
19.0.0 < https://aka.ms/OfficeSecurityReleases
Microsoft / Microsoft Office LTSC 2021
16.0.1 < https://aka.ms/OfficeSecurityReleases
Microsoft / Microsoft Office LTSC 2024
16.0.0 < https://aka.ms/OfficeSecurityReleases
Microsoft / Microsoft Office LTSC for Mac 2021
16.0.1 < 16.106.26020821
Microsoft / Microsoft Office LTSC for Mac 2024
16.0.0 < 16.106.26020821
Microsoft / Microsoft SharePoint Enterprise Server 2016
16.0.0 < 16.0.5539.1002
Microsoft / Microsoft SharePoint Server 2019
16.0.0 < 16.0.10417.20097
Microsoft / Microsoft SharePoint Server Subscription Edition
16.0.0 < 16.0.19127.20518
Microsoft / Microsoft Word 2016
16.0.1 < 16.0.5539.1002