rclone (serve s3): Path traversal in rclone's S3 gateway lets a caller read and overwrite files above the served root.

Impact

Path traversal in rclone's S3 gateway lets a caller read and overwrite files above the served root. Sites use rclone serve s3 to put an S3 front end on a scratch or dataset directory for training jobs; this turns that gateway into arbitrary read/write on the host filesystem outside the intended prefix.

Who can reach it

Any client that can reach the rclone serve s3 endpoint, with no authentication required in the advisory's rating.

What to do

Upgrade rclone to the fixed release and restart the serve process. Until then, run rclone serve s3 as an unprivileged user in a container or with a bind-mounted root so traversal cannot escape into anything that matters. No CVE ID has been assigned; track it by the GHSA.

References