Published Oct 13, 2026Sources checked Oct 21, 2026
9.8CRITICALCVSS out of 10
What this means
Review the available evidence
CVE-2026-88156 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Oct 15, 2026
Vendor remediation details
Release Notes
Vendor-listed releases
16.114.26101123
https://aka.ms/OfficeSecurityReleases
16.0.14334.20974
16.0.17932.21056
CISA KEVNot listedBased on the latest collected catalog
EPSS1.0%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-88156?
Stack-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.