CVE-2026-21260

Microsoft Outlook Spoofing Vulnerability

At a glance

Severity: HIGH 7.5
EPSS: EPSS 1.52 % · percentile 74 (2026-10-27)
State: PUBLISHED
Published: 2026-02-10
Updated: 2026-08-19
Assigner: microsoft
NVD status: Analyzed

Description

Exposure of sensitive information to an unauthorized actor in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.

Scores

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)

Weaknesses (CWE)

CWE-200

European references

ENISA EUVD · EUVD-2026-7354
GCVE · GCVE-0-2026-21260

CERT-FR advisories

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

Affected configurations (NVD CPE)

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:2024:*:*:*:*:-:x64:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*
cpe:2.3:a:microsoft:outlook:2016:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:outlook:2016:*:*:*:*:*:x86:*
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:*:*:*:*:*:*:*

Affected products

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 Outlook 2016	affected 16.0.0.0 < 16.0.5539.1002
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

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21260

Sources

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