Windows Containers EUVD-2026-100357

Requires an attacker to already hold a valid low-privileged local account on the target Windows host (PR:L, AV:L) and to interact with the Windows Container Isolation FS Filter Driver (unionfs.sys) path, abusing improper access control / link following (CWE-59) to manipulate file links that the driver resolves with elevated privileges. No user interaction is needed (UI:N) and complexity is low (AC:L). Limiting factors: exploitation is purely local - there is no remote vector, the attacker must first achieve code execution or logon as a user, and the vulnerable container-isolation filter-driver code path must be reachable/loaded on the host.

This is a genuine patch-priority issue for Windows environments, though not an emergency relative to remote/wormable flaws. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N) describes a low-complexity local elevation-of-privilege requiring only an authenticated low-privileged account and no user interaction, with full High impact to confidentiality, integrity, and availability (C:H/I:H/A:H) - consistent with CWE-59 (link following) in a kernel-mode filter driver (unionfs.sys), where a successful exploit typically yields SYSTEM. No EPSS score, CISA KEV listing, or public POC was provided in the intelligence, so there is no evidence of active exploitation or weaponization at time of analysis; the realistic signal set points to a serious-but-standard Patch-Tuesday-class EoP rather than a mass-exploited threat. Conflict to note: the input Tags label this 'Information Disclosure,' but the description and the full-impact CVSS vector clearly describe local privilege elevation - treat the tag as unreliable and prioritize as EoP. Because EoP bugs are commonly chained after initial access (phishing, commodity malware, compromised low-priv service accounts), it should be remediated on normal-to-expedited patch cadence even without KEV confirmation.

An attacker who already has a low-privileged foothold on a Windows host (e.g., a standard user account or a compromised service) abuses the Container Isolation FS Filter Driver's improper handling of file links (CWE-59) to redirect a privileged file operation to an attacker-controlled target. Exploitation is local and low-complexity with no user interaction, letting the attacker escalate to SYSTEM. No public exploit code was identified in the provided intelligence.