Vulnerability in Go standard library os

[ Why it matters ]Priority signals

• Critical severity: CVSS 9.8

[ Description ]Official 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).

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund8 Oct 2026WID-SEC-2026-3841

  Golang Go: Multiple vulnerabilities Translated from German

  Risk mediumCVE-2026-94439CVE-2026-56866CVE-2026-94447+12 more CVEs

[ References ]References

• go.dev/cl/847305
• go.dev/issue/81739
• groups.google.com/g/golang-announce/c/U2fTuyDJznI
• pkg.go.dev/vuln/GO-2026-6604