GR Board (aka grboard) 1.8.6.5 Community Edition does not require authentication for certain database actions, which allows remote attackers to modify or delete data via a request to (1) mod_rewrite.php, (2) comment_write_ok.php, (3) poll/index.php, (4) update/index.php, (5) trackback.php, or (6) an arbitrary poll.php script under theme/.