CVE-2026-69918

Summary

A heap-based buffer overflow in Windows Core Messaging allows local attackers with valid credentials to elevate their privileges to SYSTEM level. This vulnerability affects multiple Windows 10 and 11 versions and can lead to complete system compromise.

Exploitability

Exploitation requires a local authenticated user with valid credentials, making it moderately difficult but achievable through social engineering or compromised accounts, with no additional preconditions beyond standard user access.

Blast radius

If exploited, this vulnerability could affect thousands of Windows 10 and 11 systems across enterprise environments, potentially leading to widespread privilege escalation and full system compromise.

Detection

No reliable host or network indicator is derivable from the published description.

Prioritized remediation

Apply the Microsoft security update KB5040463 for Windows 10 version 1607, Windows 10 version 1809, Windows 10 version 21H2, Windows 10 version 22H2, Windows 11 version 23H2, Windows 11 version 24H2, and Windows 11 version 25H2.

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.