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Fencer Vulns
high 7.5

CVE-2026-21260 json

Microsoft Outlook Spoofing Vulnerability

published 2026-02-10 8 mo ago modified 2026-08-19 2 mo ago also EUVD-2026-7354

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

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

Patch / fix

  • Microsoft Microsoft Outlook 2016 16.0.5539.1002
  • Microsoft Microsoft SharePoint Enterprise Server 2016 16.0.5539.1002
  • Microsoft Microsoft SharePoint Server 2019 16.0.10417.20097
  • Microsoft Microsoft SharePoint Server Subscription Edition 16.0.19127.20518

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

1.50% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 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
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • Microsoft Microsoft 365 Apps for Enterprise
  • Microsoft Microsoft Office 2019
  • Microsoft Microsoft Office LTSC 2021
  • Microsoft Microsoft Office LTSC 2024
  • Microsoft Microsoft Outlook 2016
  • Microsoft Microsoft SharePoint Enterprise Server 2016
  • Microsoft Microsoft SharePoint Server 2019
  • Microsoft Microsoft SharePoint Server Subscription Edition

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.