@@ -18,6 +18,8 @@ import (

 // ApplyLayer parses a diff in the standard layer format from `layer`, and

 // applies it to the directory `dest`.

 func ApplyLayer(dest string, layer ArchiveReader) error {

+	dest = filepath.Clean(dest)

+

 	// We need to be able to set any perms

 	oldmask, err := system.Umask(0)

 	if err != nil {

@@ -91,6 +93,12 @@ func ApplyLayer(dest string, layer ArchiveReader) error {

 		path := filepath.Join(dest, hdr.Name)

 		base := filepath.Base(path)

+

+		// Prevent symlink breakout

+		if !strings.HasPrefix(path, dest) {

+			return breakoutError(fmt.Errorf("%q is outside of %q", path, dest))

+		}

+

 		if strings.HasPrefix(base, ".wh.") {

 			originalBase := base[len(".wh."):]

 			originalPath := filepath.Join(filepath.Dir(path), originalBase)