diff --git a/src/Admin/Metabox/Document_Link.php b/src/Admin/Metabox/Document_Link.php
index 83f1d82..d79dc2c 100644
--- a/src/Admin/Metabox/Document_Link.php
+++ b/src/Admin/Metabox/Document_Link.php
@@ -117,7 +117,7 @@ public function render( $post ) {
 	 */
 	public function save( $post_id ) {
 		// Verify nonce
-		if ( ! isset( $_POST['dll_document_link_nonce'] ) || ! wp_verify_nonce( $_POST['dll_document_link_nonce'], 'dll_save_document_link' ) ) {
+		if ( ! isset( $_POST['dll_document_link_nonce'] ) || ! wp_verify_nonce( wp_unslash( $_POST['dll_document_link_nonce'] ), 'dll_save_document_link' ) ) {
 			return;
 		}
 
diff --git a/src/Admin/Settings.php b/src/Admin/Settings.php
index e010d74..ca79f62 100644
--- a/src/Admin/Settings.php
+++ b/src/Admin/Settings.php
@@ -185,7 +185,9 @@ public function sanitize_document_page( $page_setting ) {
 	 */
 	public function sanitize_shortcode_settings( $args ) {
 		$existing_options = $this->get_existing_shortcode_options();
-		$option_page      = $_REQUEST['option_page'];
+		$option_page      = isset( $_REQUEST['option_page'] )
+			? sanitize_key( wp_unslash( $_REQUEST['option_page'] ) )
+			: '';
 
 		if ( ! $option_page ) {
 			return array_merge( $existing_options, $args );
diff --git a/src/Simple_Document_Library.php b/src/Simple_Document_Library.php
index 9a23570..a4cafcc 100644
--- a/src/Simple_Document_Library.php
+++ b/src/Simple_Document_Library.php
@@ -54,11 +54,22 @@ public function get_table( $output_type = 'html' ) {
 		$columns = $this->get_columns();
 
 		// Parse DataTables parameters from the AJAX request
-		$draw   = isset( $_POST['draw'] ) ? intval( $_POST['draw'] ) : 1;
-		$this->args['offset']  = isset( $_POST['start'] ) ? intval( $_POST['start'] ) : 0;
-		$this->args['rows_per_page'] = isset( $_POST['length'] ) && intval( $_POST['length'] ) !== -1 ? intval( $_POST['length'] ) : $this->args['rows_per_page'];
-		$this->args['sort_by'] = isset( $_POST['order'] ) ? $columns[$_POST['order'][0]['column']] : $this->get_orderby();
-    	$this->args['sort_order'] = isset( $_POST['order'] ) ? sanitize_key( $_POST['order'][0]['dir'] ) : $this->args['sort_order'];
+		$draw   = isset( $_POST['draw'] ) ? intval( wp_unslash( $_POST['draw'] ) ) : 1;
+		$this->args['offset']  = isset( $_POST['start'] ) ? intval( wp_unslash( $_POST['start'] ) ) : 0;
+		$this->args['rows_per_page'] = isset( $_POST['length'] ) && intval( wp_unslash( $_POST['length'] ) ) !== -1 ? intval( wp_unslash( $_POST['length'] ) ) : $this->args['rows_per_page'];
+		$order        = isset( $_POST['order'] ) && is_array( $_POST['order'] ) ? wp_unslash( $_POST['order'] ) : [];
+		$column_index = isset( $order[0]['column'] ) && is_scalar( $order[0]['column'] )
+			? filter_var( $order[0]['column'], FILTER_VALIDATE_INT )
+			: false;
+		$this->args['sort_by'] = false !== $column_index && $column_index >= 0 && isset( $columns[ $column_index ] )
+			? $columns[ $column_index ]
+			: $this->get_orderby();
+		$direction = isset( $order[0]['dir'] ) && is_scalar( $order[0]['dir'] )
+			? sanitize_key( (string) $order[0]['dir'] )
+			: '';
+		if ( in_array( $direction, [ 'asc', 'desc' ], true ) ) {
+			$this->args['sort_order'] = $direction;
+		}
     	$this->args['search_value'] = isset( $_POST['search']['value'] ) ? sanitize_text_field( wp_unslash( $_POST['search']['value'] ) ) : '';
 		$this->args['rows_per_page'] = filter_var( $this->args['rows_per_page'], FILTER_VALIDATE_INT );