Windows Go Mkdir Junction Traversal (CVE-2026-56857)
CVE-2026-56857 Published on October 8, 2026
Root.Mkdir(All) can follow junctions out of the root on Windows in os
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).
Products Associated with CVE-2026-56857
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Affected Versions
Go standard library os:- Before 1.26.9 is affected.
- Version 1.27.0-0 and below 1.27.2 is affected.
- Before 1.26.9 is affected.
- Version 1.27.0-0 and below 1.27.2 is affected.