CVE-2026-56857: Root.Mkdir(All) can follow junctions out of the root on Windows in os

Overview

Severity

Critical (CVSS 9.8)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Status

Not Exploited

Patch Tuesday

2026-Oct

Released

2026-10-11

Last Updated

2026-10-12

EPSS Score

0.49% (percentile: 40.7%)

Affected Products (2)

Other

• 21857-17084
• 21809-17084

Revision History

• 2026-10-11: Information published.
• 2026-10-12: Information published.