Diagnostic Policy Service CVE-2026-83915

Exploitation requires the attacker to already have authenticated local access with at least low-level privileges (PR:L) on the target Windows host - there is no remote or unauthenticated path. The attacker must locally interact with the Windows Diagnostic Policy Service (DPS), which is enabled and running by default on affected Windows 10, Windows 11 (21H2 through 26H2), and Windows Server 2019/2022/2025 builds listed in the EUVD data, so no special non-default feature toggle is needed. The key LIMITING factor is high attack complexity (AC:H): the use-after-free depends on a timing/race or heap-grooming condition that the attacker cannot reliably control on every attempt, reducing exploitation reliability. No user interaction is required (UI:N).

This is a moderate-priority local privilege escalation flaw, not an emergency. The CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.0 HIGH) describes a locally-exploitable use-after-free that already requires the attacker to hold low-level privileges (PR:L) and to win a difficult-to-reliably-trigger race or memory condition (AC:H). The high complexity and local-only vector meaningfully constrain real-world weaponization. Secondary signals reinforce a lower urgency than the 'HIGH' label alone suggests: CISA SSVC lists Exploitation as 'none' and Automatable as 'no', meaning no observed exploitation and no reliable mass-automation path, while only Technical Impact is 'total'. There is no CISA KEV listing and no public exploit identified at time of analysis, so there is no evidence of active exploitation. No EPSS score was provided in the input, so probabilistic exploitation likelihood could not be factored in - treat that as a data gap rather than a low score. The impact signals are internally consistent (local EoP with total technical impact maps cleanly to C:H/I:H/A:H and the SSVC 'total' rating), and nothing in the vector conflicts with the description. Net: patch on normal cadence as part of the monthly Windows rollup; this is a post-foothold escalation aid, not an initial-access or wormable threat.

An attacker who already has a low-privileged foothold on a Windows host (e.g., a standard user account or a compromised service) runs a crafted local program that manipulates the Diagnostic Policy Service to trigger a use-after-free on freed memory. By grooming the heap and winning the timing window, the attacker reuses the dangling object to run code in the service's higher-privileged context, elevating to SYSTEM. No public proof-of-concept exploit is identified at time of analysis, and the high attack complexity means reliable exploitation requires precise local timing.