Windows Audio Service EUVD-2026-73502

Exploitation requires a locally authenticated account with at least standard (low-privilege) user rights on an affected Windows 11 or Windows Server 2025 build (PR:L). Standard Windows user accounts have access to audio service APIs by default - no non-default configuration, special feature enablement, or elevated privilege is required beyond a valid local logon session. No user interaction from a third party is needed (UI:N). Exploitation is constrained to the local attack vector (AV:L): there is no network-facing exploitation path indicated by the CVSS vector or description. Windows versions not listed in the affected range (Windows 10, Windows Server 2022 and earlier) are not indicated as vulnerable based on available data, limiting exposure to the specific Windows 11 and Server 2025 build lines.

The CVSS 3.1 score of 7.8 (High) is consistent with a local privilege escalation with low attack complexity. The local attack vector (AV:L) requires that an adversary already hold a foothold on the system, which constrains opportunistic internet-facing exploitation. However, PR:L with AC:L indicates that any standard user account is sufficient and no special configuration or race condition is needed, making this a reliable second-stage escalation primitive. Full C:H/I:H/A:H impact reflects complete host compromise post-escalation. EPSS data was not provided in the input, so probabilistic exploitation likelihood is unknown. No CISA KEV listing was identified, and no public proof-of-concept code has been reported at time of analysis, suggesting this has not yet been weaponized in widespread campaigns. That said, local privilege escalation vulnerabilities in Windows system services are routinely chained with initial-access exploits (phishing, credential theft) in real-world intrusion operations, elevating practical urgency beyond the CVSS number alone for environments with active threat exposure.

An attacker who has compromised a standard user account on a Windows 11 or Server 2025 host - for example, via phishing or credential reuse - crafts a malicious audio API call that triggers the heap buffer overflow in the AudioSrv process. The overflow corrupts adjacent heap structures, allowing the attacker to redirect AudioSrv's execution to attacker-controlled shellcode, yielding a SYSTEM-level shell. No public exploit code has been identified at time of analysis, though the AC:L rating indicates the exploitation path is straightforward once local access is in hand.