diff --git a/bbs/login_check.php b/bbs/login_check.php
index fd83a67bb..a66ed1c44 100644
--- a/bbs/login_check.php
+++ b/bbs/login_check.php
@@ -31,7 +31,8 @@ if ($mb['mb_leave_date'] && $mb['mb_leave_date'] <= date("Ymd", G5_SERVER_TIME))
 }
 
 if ($config['cf_use_email_certify'] && !preg_match("/[1-9]/", $mb['mb_email_certify'])) {
-    confirm("{$mb['mb_email']} 메일로 메일인증을 받으셔야 로그인 가능합니다. 다른 메일주소로 변경하여 인증하시려면 취소를 클릭하시기 바랍니다.", G5_URL, G5_BBS_URL.'/register_email.php?mb_id='.$mb_id);
+    $ckey = md5($mb['mb_ip'].$mb['mb_datetime']);
+    confirm("{$mb['mb_email']} 메일로 메일인증을 받으셔야 로그인 가능합니다. 다른 메일주소로 변경하여 인증하시려면 취소를 클릭하시기 바랍니다.", G5_URL, G5_BBS_URL.'/register_email.php?mb_id='.$mb_id.'&ckey='.$ckey);
 }
 
 @include_once($member_skin_path.'/login_check.skin.php');
diff --git a/bbs/qawrite_update.php b/bbs/qawrite_update.php
index be8193ce3..7e1c10226 100644
--- a/bbs/qawrite_update.php
+++ b/bbs/qawrite_update.php
@@ -403,7 +403,7 @@ if($w == 'a' && $write['qa_email_recv'] && trim($write['qa_email'])) {
     include_once(G5_LIB_PATH.'/mailer.lib.php');
 
     $subject = $config['cf_title'].' '.$qaconfig['qa_title'].' 답변 알림 메일';
-    $content = nl2br(conv_unescape_nl($qa_content));
+    $content = nl2br(conv_unescape_nl(stripslashes($qa_content)));
 
     mailer($config['cf_admin_email_name'], $config['cf_admin_email'], $write['qa_email'], $subject, $content, 1);
 }
@@ -413,7 +413,7 @@ if(($w == '' || $w == 'r') && trim($qaconfig['qa_admin_email'])) {
     include_once(G5_LIB_PATH.'/mailer.lib.php');
 
     $subject = $config['cf_title'].' '.$qaconfig['qa_title'].' 질문 알림 메일';
-    $content = nl2br(conv_unescape_nl($qa_content));
+    $content = nl2br(conv_unescape_nl(stripslashes($qa_content)));
 
     mailer($config['cf_admin_email_name'], $qa_email, $qaconfig['qa_admin_email'], $subject, $content, 1);
 }
diff --git a/bbs/register_email.php b/bbs/register_email.php
index e7fc92537..2d83f2c72 100644
--- a/bbs/register_email.php
+++ b/bbs/register_email.php
@@ -6,11 +6,17 @@ $g5['title'] = '메일인증 메일주소 변경';
 include_once('./_head.php');
 
 $mb_id = substr(clean_xss_tags($_GET['mb_id']), 0, 20);
-$sql = " select mb_email, mb_datetime, mb_email_certify from {$g5['member_table']} where mb_id = '{$mb_id}' ";
+$sql = " select mb_email, mb_datetime, mb_ip, mb_email_certify from {$g5['member_table']} where mb_id = '{$mb_id}' ";
 $mb = sql_fetch($sql);
 if (substr($mb['mb_email_certify'],0,1)!=0) {
     alert("이미 메일인증 하신 회원입니다.", G5_URL);
 }
+
+$ckey = trim($_GET['ckey']);
+$key  = md5($mb['mb_ip'].$mb['mb_datetime']);
+
+if(!$ckey || $ckey != $key)
+    alert('올바른 방법으로 이용해 주십시오.', G5_URL);
 ?>
 
 <p class="rg_em_p">메일인증을 받지 못한 경우 회원정보의 메일주소를 변경 할 수 있습니다.</p>
diff --git a/bbs/register_email_update.php b/bbs/register_email_update.php
index 36fe66f8f..12287c668 100644
--- a/bbs/register_email_update.php
+++ b/bbs/register_email_update.php
@@ -3,12 +3,15 @@ include_once('./_common.php');
 include_once(G5_CAPTCHA_PATH.'/captcha.lib.php');
 include_once(G5_LIB_PATH.'/mailer.lib.php');
 
-$mb_id    = trim($_POST['mb_id']);
-$mb_email = trim($_POST['mb_email']);
+$mb_id = substr(clean_xss_tags($_POST['mb_id']), 0, 20);
+$mb_email = get_email_address(trim($_POST['mb_email']));
 
-$sql = " select mb_name, mb_datetime from {$g5['member_table']} where mb_id = '{$mb_id}' and mb_email_certify <> '' ";
+if(!$mb_id || !$mb_email)
+    alert('올바른 방법으로 이용해 주십시오.', G5_URL);
+
+$sql = " select mb_name, mb_password, mb_email, mb_datetime from {$g5['member_table']} where mb_id = '{$mb_id}' and substring(mb_email_certify, 1, 1) = '0' ";
 $mb = sql_fetch($sql);
-if ($mb) {
+if (!$mb) {
     alert("이미 메일인증 하신 회원입니다.", G5_URL);
 }
 
diff --git a/bbs/write_update.php b/bbs/write_update.php
index 0bf65612e..4bf43a4ac 100644
--- a/bbs/write_update.php
+++ b/bbs/write_update.php
@@ -607,7 +607,7 @@ if (!($w == 'u' || $w == 'cu') && $config['cf_email_use'] && $board['bo_use_emai
     else if (strstr($html, 'html2'))
         $tmp_html = 2;
 
-    $wr_content = conv_content(conv_unescape_nl($wr_content), $tmp_html);
+    $wr_content = conv_content(conv_unescape_nl(stripslashes($wr_content)), $tmp_html);
 
     $warr = array( ''=>'입력', 'u'=>'수정', 'r'=>'답변', 'c'=>'코멘트', 'cu'=>'코멘트 수정' );
     $str = $warr[$w];
diff --git a/common.php b/common.php
index 079473bf3..ba1580e2e 100644
--- a/common.php
+++ b/common.php
@@ -227,8 +227,10 @@ $qstr = '';
 
 if (isset($_REQUEST['sca']))  {
     $sca = clean_xss_tags(trim($_REQUEST['sca']));
-    if ($sca)
+    if ($sca) {
+        $sca = preg_replace("/[\<\>\'\"\\\'\\\"\%\=\(\)]/", "", $sca);
         $qstr .= '&amp;sca=' . urlencode($sca);
+    }
 } else {
     $sca = '';
 }
diff --git a/config.php b/config.php
index 15cf62fb1..087d32ba7 100644
--- a/config.php
+++ b/config.php
@@ -5,7 +5,7 @@
 ********************/
 
 define('G5_VERSION', '그누보드5');
-define('G5_GNUBOARD_VER', '5.1.11');
+define('G5_GNUBOARD_VER', '5.1.12');
 
 // 이 상수가 정의되지 않으면 각각의 개별 페이지는 별도로 실행될 수 없음
 define('_GNUBOARD_', true);
diff --git a/head.sub.php b/head.sub.php
index e70da0c59..00220f503 100644
--- a/head.sub.php
+++ b/head.sub.php
@@ -74,11 +74,9 @@ var g5_bo_table  = "<?php echo isset($bo_table)?$bo_table:''; ?>";
 var g5_sca       = "<?php echo isset($sca)?$sca:''; ?>";
 var g5_editor    = "<?php echo ($config['cf_editor'] && $board['bo_use_dhtml_editor'])?$config['cf_editor']:''; ?>";
 var g5_cookie_domain = "<?php echo G5_COOKIE_DOMAIN ?>";
-<?php
-if ($is_admin) {
-    echo 'var g5_admin_url = "'.G5_ADMIN_URL.'";'.PHP_EOL;
-}
-?>
+<?php if(defined('G5_IS_ADMIN')) { ?>
+var g5_admin_url = "<?php echo G5_ADMIN_URL; ?>";
+<?php } ?>
 </script>
 <script src="<?php echo G5_JS_URL ?>/jquery-1.8.3.min.js"></script>
 <script src="<?php echo G5_JS_URL ?>/jquery.menu.js"></script>
diff --git a/theme/basic/head.sub.php b/theme/basic/head.sub.php
index 6eb194fdc..33998c4e1 100644
--- a/theme/basic/head.sub.php
+++ b/theme/basic/head.sub.php
@@ -61,11 +61,6 @@ var g5_bo_table  = "<?php echo isset($bo_table)?$bo_table:''; ?>";
 var g5_sca       = "<?php echo isset($sca)?$sca:''; ?>";
 var g5_editor    = "<?php echo ($config['cf_editor'] && $board['bo_use_dhtml_editor'])?$config['cf_editor']:''; ?>";
 var g5_cookie_domain = "<?php echo G5_COOKIE_DOMAIN ?>";
-<?php
-if ($is_admin) {
-    echo 'var g5_admin_url = "'.G5_ADMIN_URL.'";'.PHP_EOL;
-}
-?>
 </script>
 <script src="<?php echo G5_JS_URL ?>/jquery-1.8.3.min.js"></script>
 <script src="<?php echo G5_JS_URL ?>/jquery.menu.js"></script>
@@ -75,6 +70,8 @@ if ($is_admin) {
 if(G5_IS_MOBILE) {
     echo '<script src="'.G5_JS_URL.'/modernizr.custom.70111.js"></script>'.PHP_EOL; // overflow scroll 감지
 }
+if(!defined('G5_IS_ADMIN'))
+    echo $config['cf_add_script'];
 ?>
 </head>
 <body>