OnlyPatch
Microsoft Office Outlook

CVE-2026-21260 — Microsoft Outlook Spoofing Vulnerability

Important CVSS 7.5 EPSS 0.01425 2026-02 archive

Executive Summary

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

Overview

7.5
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Exploitation Unlikely
MS Exploit Likelihood
Category Spoofing
Weakness CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Released Feb 10 2026
Last Updated Feb 10 2026
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.01425 — 0.70158 percentile
NVD CVSS 7.5 HIGH — matches MSRC

CVSS Vector

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
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
None
AVAILABILITY
None
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.5

EPSS Score

0.01425
probability of exploitation in the next 30 days
0.70158 percentile - updated 2026-07-25
View on FIRST.org

Affected Products

11 affected products
Product KB Article Severity Impact Restart Required
Microsoft 365 Apps for Enterprise for 32-bit Systems Click to Run (Security Update) Important Spoofing No
Microsoft 365 Apps for Enterprise for 64-bit Systems Click to Run (Security Update) Important Spoofing No
Microsoft Office 2019 for 32-bit editions Click to Run (Security Update) Important Spoofing No
Microsoft Office 2019 for 64-bit editions Click to Run (Security Update) Important Spoofing No
Microsoft Office LTSC 2021 for 32-bit editions Click to Run (Security Update) Important Spoofing No
Microsoft Office LTSC 2021 for 64-bit editions Click to Run (Security Update) Important Spoofing No
Microsoft Office LTSC 2024 for 32-bit editions Click to Run (Security Update) Important Spoofing No
Microsoft Office LTSC 2024 for 64-bit editions Click to Run (Security Update) Important Spoofing No
Microsoft Outlook 2016 (32-bit edition) 5002839 (Security Update) Important Spoofing Maybe
Microsoft Outlook 2016 (64-bit edition) 5002839 (Security Update) Important Spoofing Maybe
Microsoft SharePoint Enterprise Server 2016 5002841 (Security Update) 5002840 (Security Update) Important Spoofing 5002828 5002827 Base: 7.5 Temporal: 6.5 Vector: 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 16.0.5539.1002 Maybe None Microsoft SharePoint Server 2019 5002834 (Security Update) 5002836 (Security Update) Important Spoofing 5002825 5002823 Base: 7.5 Temporal: 6.5 Vector: 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 16.0.10417.20097 Maybe None Microsoft SharePoint Server Subscription Edition 5002833 (Security Update) Important Spoofing Maybe

Patches

3 patches
Article Type Restart
Click to Run Security Update No
5002839 Security Update Maybe
5002833 Security Update Maybe

Known Exploits

Acknowledgments

ErPaciocco

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