(1) ApiBlock.php, (2) ApiCreateAccount.php, (3) ApiLogin.php, (4) ApiMain.php, (5) ApiQueryDeletedrevs.php, (6) ApiTokens.php, and (7) ApiUnblock.php in includes/api/ in MediaWiki 1.19.x before 1.19.8, 1.20.x before 1.20.7, and 1.21.x before 1.21.2 allow remote attackers to obtain CSRF tokens and bypass the cross-site request forgery (CSRF) protection mechanism via a JSONP request to wiki/api.php.