Windows MIDI Service CVE-2026-69508

Requires an authenticated local user account (PR:L); remote unauthenticated exploitation is not possible given AV:L. The attacker must be able to invoke or interact with the Windows MIDI Service Module, which is a default Windows 11 component and does not require special configuration to be present. No user interaction is required (UI:N) and attack complexity is low (AC:L), meaning no race conditions or additional prerequisites beyond local access apply. Exploitation is limited to Windows 11 versions 24H2, 25H2, and 26H1; earlier Windows versions and Windows 10 are not listed as affected.

The CVSS 3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H yields a score of 7.8, accurately reflecting the local-access prerequisite and low-complexity exploitation path. The AV:L constraint limits opportunistic mass exploitation, but the AC:L/UI:N combination means any unprivileged local user - including users on shared systems, RDP sessions, or virtual desktop environments - can reliably exploit this without needing additional conditions or victim interaction. The scope is contained (S:U), yet C:H/I:H/A:H indicates complete system compromise once exploited. No EPSS score was provided in the input, and this CVE does not appear in CISA KEV, suggesting exploitation has not been observed at scale at time of analysis. No public POC code was identified in the input data. Despite the absence of active exploitation signals, the low complexity and no-interaction requirements make this a credible post-access privilege escalation tool - even a mid-sized IT operation should treat patching as urgent given the breadth of affected Windows 11 versions. The patch availability from Microsoft removes the need for compensating controls as the primary response.

An attacker with a standard local user account on an unpatched Windows 11 system crafts a malformed MIDI API call or data payload targeting the vulnerable buffer in the MIDI Service Module. The overflow overwrites the saved return address on the stack, redirecting execution to attacker-controlled shellcode or a ROP chain. Execution continues in the security context of the MIDI service (SYSTEM), granting the attacker full administrative control of the host.