Windows NTFS CVE-2026-56175

Exploitation requires the attacker to already have local, authenticated code-execution as a low-privileged user on the target Windows host (CVSS PR:L, AV:L) - this is a second-stage privilege-escalation bug, not a remote entry point. No user interaction is needed (UI:N) and attack complexity is low (AC:L), so once a foothold exists the trigger is reliable. The limiting factors that reduce real-world risk are therefore the need for a pre-existing local session and the fact that it cannot be launched over the network; the affected NTFS driver is present in default configurations of every listed Windows and Windows Server build, so no special feature or non-default setting is required beyond having the standard OS installed.

The signals are internally consistent and point to a genuine but not emergency-tier priority. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N, C:H/I:H/A:H, S:U) describes a local, low-complexity attack requiring an existing low-privileged foothold, with full compromise of confidentiality, integrity, and availability once triggered - the classic profile of a SYSTEM-level EoP. No EPSS score was supplied; the vulnerability is not in CISA KEV and no POC is referenced, so this is 'no public exploit identified at time of analysis' rather than confirmed exploitation. There is no data conflict: description ('elevate privileges locally') and vector (AV:L, PR:L) agree. The realistic risk is that this becomes a reliable exploitation-chain component (paired with a separate RCE or phishing foothold) - the kind of NTFS/kernel EoP Microsoft frequently sees weaponized after patch release - so it warrants prompt patching even absent current in-the-wild activity.

An attacker who has already gained a standard (non-admin) user session - for example via phishing malware or a compromised service account - invokes the vulnerable NTFS code path with crafted input that overflows a kernel heap buffer. By grooming the heap and corrupting adjacent kernel structures, they escalate to SYSTEM and disable defenses or install persistence. No public POC is currently identified, and the local attack vector means the attacker needs prior code execution on the host.