Path traversal in Go programming language - CVE-2026-27139

Detailed vulnerability description

The vulnerability allows a local user to access file metadata outside the intended root directory.

The vulnerability exists due to improper handling of symbolic links in os.FileInfo when listing directory contents via File.ReadDir or File.Readdir on Unix platforms. A local user can replace a path component with a symbolic link to cause lstat to access a file outside the root, allowing metadata disclosure.

The impact is limited to reading file metadata such as size and existence; it does not allow reading or modifying file contents. The user must have access to the directory being listed and the ability to create or modify symbolic links within the path.

How to mitigate CVE-2026-27139

Sources

• https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk
• https://go.dev/issue/77827