diff --git a/easy-image-gallery.php b/easy-image-gallery.php
index a03e4f8..b4f9522 100644
--- a/easy-image-gallery.php
+++ b/easy-image-gallery.php
@@ -3,7 +3,7 @@
 Plugin Name: Easy Image Gallery
 Plugin URI: https://devrix.com/
 Description: An easy to use image gallery with drag & drop re-ordering
-Version: 1.5.4
+Version: 1.5.5
 Author: DevriX
 Author URI: https://devrix.com/
 Text Domain: easy-image-gallery
diff --git a/includes/metabox.php b/includes/metabox.php
index bdf9df4..40087d7 100644
--- a/includes/metabox.php
+++ b/includes/metabox.php
@@ -100,7 +100,7 @@ function easy_image_gallery_metabox() {
 						$get_galleries = array(
 							array(
 								array(
-									'SHORTCODE'   => wp_rand( 100, 999 ),
+									'SHORTCODE'   => (string) wp_rand( 100000, 999999999 ),
 									'DATA'        => $get_gallery_old_data,
 									'OPEN_IMAGES' => $get_open_images[0],
 								),
@@ -110,8 +110,21 @@ function easy_image_gallery_metabox() {
 
 					$gallery_count = -1;
 					if ( isset( $get_galleries ) && ! empty( $get_galleries ) ) {
+						$existing_shortcodes = array();
+
 						foreach ( $get_galleries[0] as $gallery ) {
 							$gallery_count   = $gallery_count + 1;
+
+							$gallery_shortcode = easy_image_gallery_sanitize_gallery_id( $gallery['SHORTCODE'] );
+							if ( '' === $gallery_shortcode || in_array( $gallery_shortcode, $existing_shortcodes, true ) ) {
+								do {
+									$candidate = (string) wp_rand( 100000, 999999999 );
+								} while ( in_array( $candidate, $existing_shortcodes, true ) );
+
+								$gallery_shortcode = $candidate;
+							}
+
+							$existing_shortcodes[] = $gallery_shortcode;
 							$get_attachments = $gallery['DATA'];
 
 							// Convert attachements to string
@@ -139,8 +152,8 @@ function easy_image_gallery_metabox() {
 									<a href="#" class="dx-eig-gallery-add-images button" data-count="<?php echo esc_attr( (string) $gallery_count ); ?>"><?php esc_html_e( 'Add images to the gallery', 'easy-image-gallery' ); ?></a>
 									<span class="eig-remove"><img src="<?php echo esc_url( EASY_IMAGE_GALLERY_URL . 'includes/fonts/close.png' ); ?>" alt=""></span>
 									<a href="#" class="button button-primary button-small dx-eig-insert-shortcode">Insert this shortcode in the content</a>
-									<input type="text" class="dx-eig-shortcode" name="image_gallery[<?php echo esc_attr( (string) $gallery_count ); ?>][SHORTCODE]" value="<?php echo esc_attr( (string) $gallery['SHORTCODE'] ); ?>" hidden>
-									<input type="text" class="dx-eig-shortcode-show" readonly="" value="<?php echo esc_attr( '[easy_image_gallery gallery="' . $gallery['SHORTCODE'] . '"]' ); ?>">
+									<input type="text" class="dx-eig-shortcode" name="image_gallery[<?php echo esc_attr( (string) $gallery_count ); ?>][SHORTCODE]" value="<?php echo esc_attr( $gallery_shortcode ); ?>" hidden>
+									<input type="text" class="dx-eig-shortcode-show" readonly="" value="<?php echo esc_attr( '[easy_image_gallery gallery="' . $gallery_shortcode . '"]' ); ?>">
 									<div class="link-image-to-l">
 										<label for="easy_image_gallery_link_images_<?php echo esc_attr( (string) $gallery_count ); ?>">
 											<input type="checkbox" id="easy_image_gallery_link_images_<?php echo esc_attr( (string) $gallery_count ); ?>" value="on" name="image_gallery[<?php echo esc_attr( (string) $gallery_count ); ?>][OPEN_IMAGES]" <?php checked( isset( $gallery['OPEN_IMAGES'] ) ? $gallery['OPEN_IMAGES'] : '', 'on' ); ?> /> <?php esc_html_e( 'Link images to larger sizes', 'easy-image-gallery' ); ?>
@@ -398,6 +411,8 @@ function easy_image_gallery_save_post( $post_id ) {
 
 		$easy_image_gallery_post = map_deep( wp_unslash( $_POST['image_gallery'] ), 'sanitize_text_field' );
 
+		$existing_shortcodes = array();
+
 		foreach ( $easy_image_gallery_post as $gallery ) {
 			if ( ! is_array( $gallery ) ) {
 				continue;
@@ -412,7 +427,22 @@ function easy_image_gallery_save_post( $post_id ) {
 			}
 
 			$gallery['DATA'] = $convert_to_arr;
-			$galleries[]     = $gallery;
+
+			if ( isset( $gallery['SHORTCODE'] ) ) {
+				$gallery['SHORTCODE'] = easy_image_gallery_sanitize_gallery_id( $gallery['SHORTCODE'] );
+
+				if ( '' === $gallery['SHORTCODE'] || in_array( $gallery['SHORTCODE'], $existing_shortcodes, true ) ) {
+					do {
+						$candidate = (string) wp_rand( 100000, 999999999 );
+					} while ( in_array( $candidate, $existing_shortcodes, true ) );
+
+					$gallery['SHORTCODE'] = $candidate;
+				}
+
+				$existing_shortcodes[] = $gallery['SHORTCODE'];
+			}
+
+			$galleries[] = $gallery;
 		}
 
 		update_post_meta( $post_id, '_easy_image_gallery_v2', $galleries );
diff --git a/includes/template-functions.php b/includes/template-functions.php
index 5903ead..3b95323 100644
--- a/includes/template-functions.php
+++ b/includes/template-functions.php
@@ -106,7 +106,7 @@ function easy_image_gallery_get_image_ids( $post_id = null, $all_galleries_image
 
 				if( isset( $new_db_structure ) && !empty( $new_db_structure ) ){
 					foreach( $new_db_structure as $gallery ){
-						if( $gallery['SHORTCODE'] == $gallery_id ){
+						if ( (string) easy_image_gallery_sanitize_gallery_id( $gallery['SHORTCODE'] ) === (string) easy_image_gallery_sanitize_gallery_id( $gallery_id ) ) {
 							return $gallery['DATA'];
 						}
 					}
@@ -216,43 +216,65 @@ function easy_image_gallery_get_lightbox() {
 endif;
 
 
+/**
+ * Sanitize a gallery/shortcode ID for safe use in HTML attributes and selectors.
+ *
+ * Gallery IDs are numeric (see wp_rand-generated SHORTCODE values in the metabox).
+ *
+ * @since 1.5.5
+ * @param mixed $gallery_id Gallery identifier.
+ * @return string Digits-only ID, or empty string when invalid.
+ */
+function easy_image_gallery_sanitize_gallery_id( $gallery_id ) {
+	if ( null === $gallery_id || '' === $gallery_id || 'old_db' === $gallery_id ) {
+		return '';
+	}
+
+	$sanitized_gallery_id = preg_replace( '/[^0-9]/', '', (string) $gallery_id );
+
+	if ( '' === $sanitized_gallery_id ) {
+		return '';
+	}
+
+	return $sanitized_gallery_id;
+}
+
 /**
  * Returns the correct rel attribute for the anchor links
  *
  * @since 1.0
  * @return string
  */
-
 function easy_image_gallery_lightbox_rel( $gallery_id = null ) {
 
-	$lightbox = easy_image_gallery_get_lightbox();
+	$gallery_id = easy_image_gallery_sanitize_gallery_id( $gallery_id );
+	$lightbox   = easy_image_gallery_get_lightbox();
 
 	switch ( $lightbox ) {
 
 	case 'prettyphoto':
 
-		$rel = 'rel="prettyPhoto' . '[group-'.$gallery_id.']"';
+		$rel = 'rel="' . esc_attr( 'prettyPhoto[group-' . $gallery_id . ']' ) . '"';
 
 		break;
 
 	case 'fancybox':
 
-		$rel = 'data-fancybox="gallery'.$gallery_id.'"';
+		$rel = 'data-fancybox="' . esc_attr( 'gallery' . $gallery_id ) . '"';
 
 		break;
 
 	case 'luminous':
 
-		$rel = 'rel="luminous'  . '[group-'.$gallery_id.']"';
+		$rel = 'rel="' . esc_attr( 'luminous[group-' . $gallery_id . ']' ) . '"';
 
 		break;
 
 	default:
 
-		$rel = 'rel="prettyPhoto' . '[group-'.$gallery_id.']"';
+		$rel = 'rel="' . esc_attr( 'prettyPhoto[group-' . $gallery_id . ']' ) . '"';
 	}
 
-
 	return $rel;
 }
 
@@ -362,15 +384,27 @@ function easy_image_gallery_get_galleries() {
 function easy_image_gallery_shortcode( $atts ) {
 
 	// return early if the post type is not allowed to have a gallery
-	if ( !easy_image_gallery_allowed_post_type() ){
-        return;
-    }else{
-        if ( isset($atts['gallery']) && !empty($atts['gallery']) ){
-            return easy_image_gallery( $atts['gallery'] );
-        }else{
-	        return easy_image_gallery( 'old_db' );
-        }
-    }
+	if ( ! easy_image_gallery_allowed_post_type() ) {
+		return '';
+	}
+
+	$atts = shortcode_atts(
+		array(
+			'gallery' => '',
+		),
+		$atts,
+		'easy_image_gallery'
+	);
+
+	if ( ! empty( $atts['gallery'] ) ) {
+		$gallery_id = easy_image_gallery_sanitize_gallery_id( $atts['gallery'] );
+		if ( '' !== $gallery_id ) {
+			return easy_image_gallery( $gallery_id );
+		}
+		return '';
+	}
+
+	return easy_image_gallery( 'old_db' );
 }
 add_shortcode( 'easy_image_gallery', 'easy_image_gallery_shortcode' );
 
@@ -387,7 +421,7 @@ function easy_image_gallery_count_images( $gallery_shortcode ) {
 
 	if ( isset($galleries) && !empty($galleries) ) {
         foreach ( $galleries as $gallery ){
-            if ( $gallery['SHORTCODE'] == $gallery_shortcode ){
+            if ( (string) easy_image_gallery_sanitize_gallery_id( $gallery['SHORTCODE'] ) === (string) easy_image_gallery_sanitize_gallery_id( $gallery_shortcode ) ) {
                 $number = count($gallery['DATA']);
                 return $number;
             }
@@ -412,11 +446,24 @@ function easy_image_gallery( $gallery_id = 'old_db' ) {
         ob_start();
         foreach ($galleries as $gallery){
 
-            if ($gallery_id == 'old_db'){
-                $gallery_id = $gallery['SHORTCODE'];
-            }
+			$current_gallery_id = $gallery_id;
+
+			if ( 'old_db' === $current_gallery_id ) {
+				$candidate = easy_image_gallery_sanitize_gallery_id( $gallery['SHORTCODE'] );
+				if ( '' === $candidate ) {
+					// Couldn't derive a valid numeric ID from this gallery; try the next one.
+					continue;
+				}
+
+				$current_gallery_id = $candidate;
+			} else {
+				$current_gallery_id = easy_image_gallery_sanitize_gallery_id( $current_gallery_id );
+				if ( '' === $current_gallery_id ) {
+					continue;
+				}
+			}
 
-            if ( $gallery['SHORTCODE'] == $gallery_id ){
+			if ( (string) easy_image_gallery_sanitize_gallery_id( $gallery['SHORTCODE'] ) === (string) $current_gallery_id ) {
                 $gallery_exist = true;
 
                 $has_gallery_images = $gallery['DATA'];
@@ -458,10 +505,10 @@ function easy_image_gallery( $gallery_id = 'old_db' ) {
 
 	                        $lightbox = easy_image_gallery_get_lightbox();
 
-	                        $rel =  easy_image_gallery_lightbox_rel( $gallery_id );
+							$rel =  easy_image_gallery_lightbox_rel( $current_gallery_id );
 
 	                        if ( isset($gallery['OPEN_IMAGES']) && $gallery['OPEN_IMAGES'] == 'on' )
-	                            $html = sprintf( '<li><a %s href="%s" class="%s" title="%s" data-caption="%s" target="_blank"><i class="icon-view"></i><span class="overlay"></span>%s</a></li>', $rel, $image_link, $image_class, $image_caption, $image_caption, $image );
+	                            $html = sprintf( '<li><a %s href="%s" class="%s" title="%s" data-caption="%s" target="_blank"><i class="icon-view"></i><span class="overlay"></span>%s</a></li>', $rel, esc_url( $image_link ), $image_class, $image_caption, $image_caption, $image );
 	                        else
 	                            $html = sprintf( '<li>%s</li>', $image );
 
@@ -470,7 +517,7 @@ function easy_image_gallery( $gallery_id = 'old_db' ) {
                 	echo '</ul>';
 
                 	if ( easy_image_gallery_get_lightbox() === 'luminous' ) {
-						$luminous_selector = sprintf( "a[rel='luminous[group-%s]']", $gallery_id );
+						$luminous_selector = sprintf( "a[rel='luminous[group-%s]']", easy_image_gallery_sanitize_gallery_id( $current_gallery_id ) );
 						printf(
 							'<script>new LuminousGallery(document.querySelectorAll(%s));</script>',
 							wp_json_encode( $luminous_selector )
diff --git a/readme.txt b/readme.txt
index beb2962..f7f5fa3 100644
--- a/readme.txt
+++ b/readme.txt
@@ -3,7 +3,7 @@ Contributors: devrix, nofearinc
 Tags: image gallery, image, galleries, simple, easy, devrix
 Requires at least: 3.5
 Tested up to: 6.9.4
-Stable tag: 1.5.4
+Stable tag: 1.5.5
 Requires PHP: 7.4.0
 License: GPLv2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html
@@ -118,6 +118,10 @@ The plugin ownership was transferred to DevriX. There are no functionality chang
 
 == Changelog ==
 
+= 1.5.5 =
+* Security: Escape gallery IDs in lightbox HTML attributes (fancybox, prettyPhoto, luminous) to prevent stored XSS via shortcode or post meta.
+* Security: Sanitize gallery IDs on save and in the [easy_image_gallery] shortcode.
+
 = 1.5.4 = 
 * Fixed vulnerability report
 * Tested up to WordPress 6.9.4