Windows Kernel EUVD-2026-100099

Exploitation requires the attacker to already have local, authenticated access with at least low privileges (PR:L) on an affected Windows build - there is no remote or network vector (AV:L) and no user interaction by a victim is needed (UI:N). The high attack complexity (AC:H) indicates a meaningful limiting factor, typically a race condition or specific timing/heap state needed to win the use-after-free, so exploitation is not deterministic. Affected builds are specific: Windows 11 24H2 (<10.0.26100.9711), 25H2 (<10.0.26200.9711), 26H1 (<10.0.28000.3231), 26H2 (<10.0.26300.9711), and Windows Server 2025 including Server Core (<10.0.26100.33650); systems patched to or above these build numbers are not exploitable.

Signals are largely consistent and point to a genuine but not top-tier priority. The CVSS 3.1 vector (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.0 HIGH) describes local, authenticated (PR:L) exploitation with high attack complexity (AC:H) yielding full confidentiality, integrity, and availability impact - classic kernel privilege escalation. CISA's SSVC framework reinforces a measured posture: Exploitation=none (no observed or public exploitation), Automatable=no (consistent with AC:H and the need for an existing low-privilege foothold), but Technical Impact=total (consistent with C:H/I:H/A:H kernel compromise). KEV status is not listed, no POC is reported, and no EPSS score was provided, so exploitation probability cannot be quantified from the input - the absence of EPSS is a data gap, not a signal of safety. In short, this is a high-impact-but-constrained issue: it is not a drive-by remote bug and requires attacker code already running on the host, so it is best treated as a reliable second-stage privilege-escalation primitive to be patched on a normal-to-expedited cadence rather than an emergency. The 'Denial Of Service' tag conflicts with the description, which explicitly states privilege elevation, not DoS - verify categorization.

An attacker who already has a low-privileged foothold on a Windows host (via phishing, a malicious installer, or a compromised standard user account) runs a crafted program that triggers the use-after-free in the Windows Kernel, reclaiming the freed object to corrupt kernel memory and elevate to SYSTEM. No public exploit code is identified at time of analysis, and the high attack complexity (AC:H) implies a race condition or precise heap-grooming is needed, so reliable exploitation is non-trivial.