GHSA-5ww9-jg6q-38r7: File Browser: Cross-user unauthorized share-link deletion via unbounded prefix match in DeleteWithPathPrefix

Summary A low-privileged authenticated user of filebrowser (with create + delete permissions in their own isolated scope) can silently destroy share-link records belonging to any other user — including the administrator — by performing a legitimate DELETE on a file in their own directory whose logical path happens to be a byte-prefix of another user's stored share.Link.Path. The file contents of the victim are not exposed, but the victim's share links are irrevocably wiped. Details resourceDeleteHandler in http/resource.go cleans up any share records that reference a deleted file by calling: // http/resource.go err = d.store.Share.DeleteWithPathPrefix(file.Path) file.Path here is the *logical* path from the URL of the deleting user's request (e.g. /a), not the absolute filesystem path. It is passed as-is to the bolt backend: // storage/bolt/share.go func (s shareBackend) DeleteWithPathPrefix(pathPrefix string) error { var links []share.Link if err := s.db.Prefix("Path", pathPrefix, &links); err != nil { return err } for _, link := range links { err = errors.Join(err, s.db.DeleteStruct(&share.Link{Hash: link.Hash})) } return err } Why the design contradicts this behavior. share.Link carries a UserID field and the application elsewhere treats shares as per-user owned resources. shareDeleteHandler explicitly enforces link.UserID != d.user.ID && !d.user.Perm.Admin → 403. The file-deletion side-effect path is the only location that bypasses this rule. Impact - Integrity: unauthorized deletion of share-link metadata belonging to arbitrary users, including administrators. - Availability: effective denial-of-service of the share-link feature — a cooperating (or malicious) low-priv user can wipe the bulk of existing share links by iterating a short set of one- and two-character prefixes.