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CVE-2026-21260VulnerabilityPublished Updated

CVE-2026-21260: Microsoft 365 Apps for Enterprise · Information Exposure

Affects Microsoft 365 Apps for EnterpriseSource CVE Database V5

0

Not known to be exploited · CVSS 7.5 High : upgrade to 16.0.5539.1002 soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.5% chance of exploitation in 30 days – higher than 74% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 16.0.5539.1002, 16.0.10417.20097, 16.0.19127.20518
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Upgrade Microsoft to 16.0.5539.1002 (2016) or 16.0.10417.20097 (SharePoint Server 2019) or 16.0.19127.20518 (SharePoint Server Subscription Edition).

Affected software

ProductAffectedFixed in
MicrosoftMicrosoft 365 Apps for EnterpriseAffected
  • =16.0.1
Fixed in–
MicrosoftMicrosoft Office 2019Affected
  • =19.0.0
Fixed in–
MicrosoftMicrosoft Office LTSC 2021Affected
  • =16.0.1
Fixed in–
MicrosoftMicrosoft Office LTSC 2024Affected
  • =16.0.0
Fixed in–
MicrosoftMicrosoft Outlook 2016Affected
  • >=16.0.0.0 <16.0.5539.1002
Fixed in
  • 16.0.5539.1002
MicrosoftMicrosoft SharePoint Enterprise Server 2016Affected
  • >=16.0.0 <16.0.5539.1002
Fixed in
  • 16.0.5539.1002
MicrosoftMicrosoft SharePoint Server 2019Affected
  • >=16.0.0 <16.0.10417.20097
Fixed in
  • 16.0.10417.20097
MicrosoftMicrosoft SharePoint Server Subscription EditionAffected
  • >=16.0.0 <16.0.19127.20518
Fixed in
  • 16.0.19127.20518

AI-suggested

An official fix is available from Microsoft, and remediation is managed by the vendor for this cloud-hosted service. Users and administrators should apply the official updates as provided in the Microsoft security advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21260 to mitigate this vulnerability.

Description

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

References

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