CVE-2026-56857CWE-1386

CVE-2026-56857

Critical · published October 9, 2026

CVSS v3.1
9.8
EPSS
0%
Percentile
41.5
In the wild
Unconfirmed
What it is

On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target).

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00493 · 41.5th percentile
Weakness
CWE-1386 · Insecure Operation on Windows Junction / Mount Point
Published
2026-10-09T03:17Z
References (4)
EPSS history
Timeline
  • 10 OCT 03:30Z
    EPSS moved — → 0%
    epss
  • 08 OCT 22:53Z
    Root.Mkdir(All) can follow junctions out of the root on Windows in os
    cvelistv5
  • 08 OCT 22:53Z
    Root.Mkdir(All) can follow junctions out of the root on Windows in os
    cvelistv5