CVE-2026-39822

Description

On Unix systems, opening a file in an os.Root improperly follows symlinks to locations outside of the Root when the final path component of the a path is a symbolic link and the path ends in /. For example, 'root.Open("symlink/")' will open "symlink" even when "symlink" is a symbolic link pointing outside of the root.

CVSS Metrics

• v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Techniques & Countermeasures

• CWE-61•UNIX Symbolic Link (Symlink) Following

  The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.

Affected Systems

• go standard library•os

  < 1.25.12 | ≥ 1.26.0-0, < 1.26.5 | ≥ 1.27.0-0, < 1.27.0-rc.2

• Go•stdlib

  ≥ 1.27.0-0, < 1.27.0-rc.2

References (4)

• https://go.dev/issue/79005
• https://groups.google.com/g/golang-announce/c/OrmQE_Yp5Sc
• https://go.dev/cl/797880
• https://pkg.go.dev/vuln/GO-2026-4970