Critical severity · published Oct 8, 2026
CVE-2026-56857
Root.Mkdir(All) can follow junctions out of the root on Windows in os
9.8
CVSS
0.6%
EPSS
No
On KEV
Description
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).
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 46% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
IN
internal/syscall/windows · Go standard library
before 1.26.9; 1.27.0-0 before 1.27.2 · source: vendor
OS
os · Go standard library
before 1.26.9; 1.27.0-0 before 1.27.2 · source: vendor