CVE-2026-21511

Microsoft Outlook Spoofing Vulnerability

At a glance

Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.

Version	Score	Vector	Scored by
CVSS 3.1	HIGH 7.5	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	microsoft
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N	NVD · secure@microsoft.com (Secondary)

CERTFR-2026-AVI-0153 — Multiples vulnérabilités dans les produits Microsoft · cert.ssi.gouv.fr
CERTFR-2026-AVI-0149 — Multiples vulnérabilités dans Microsoft Office · cert.ssi.gouv.fr

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:macos:*:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x64:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:macos:*:*
cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:* < 16.0.19127.20518
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x86:*

Product	Versions
Microsoft · Microsoft 365 Apps for Enterprise	affected 16.0.1 < https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office 2019	affected 19.0.0 < https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office LTSC 2021	affected 16.0.1 < https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office LTSC 2024	affected 16.0.0 < https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office LTSC for Mac 2021	affected 16.0.1 < 16.106.26020821
Microsoft · Microsoft Office LTSC for Mac 2024	affected 16.0.0 < 16.106.26020821
Microsoft · Microsoft SharePoint Enterprise Server 2016	affected 16.0.0 < 16.0.5539.1002
Microsoft · Microsoft SharePoint Server 2019	affected 16.0.0 < 16.0.10417.20097
Microsoft · Microsoft SharePoint Server Subscription Edition	affected 16.0.0 < 16.0.19127.20518
Microsoft · Microsoft Word 2016	affected 16.0.1 < 16.0.5539.1002

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD