diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-admin/includes/class-walker-category-checklist.php
--- a/wp/wp-admin/includes/class-walker-category-checklist.php	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-admin/includes/class-walker-category-checklist.php	Fri Sep 05 18:52:52 2025 +0200
@@ -107,11 +107,13 @@
 				/** This filter is documented in wp-includes/category-template.php */
 				esc_html( apply_filters( 'the_category', $category->name, '', '' ) ) . '</div>';
 		} else {
-			$is_selected = in_array( $category->term_id, $args['selected_cats'], true );
-			$is_disabled = ! empty( $args['disabled'] );
+			$is_selected         = in_array( $category->term_id, $args['selected_cats'], true );
+			$is_disabled         = ! empty( $args['disabled'] );
+			$li_element_id       = wp_unique_prefixed_id( "in-{$taxonomy}-{$category->term_id}-" );
+			$checkbox_element_id = wp_unique_prefixed_id( "in-{$taxonomy}-{$category->term_id}-" );
 
-			$output .= "\n<li id='{$taxonomy}-{$category->term_id}'$class>" .
-				'<label class="selectit"><input value="' . $category->term_id . '" type="checkbox" name="' . $name . '[]" id="in-' . $taxonomy . '-' . $category->term_id . '"' .
+			$output .= "\n<li id='" . esc_attr( $li_element_id ) . "'$class>" .
+				'<label class="selectit"><input value="' . $category->term_id . '" type="checkbox" name="' . $name . '[]" id="' . esc_attr( $checkbox_element_id ) . '"' .
 				checked( $is_selected, true, false ) .
 				disabled( $is_disabled, true, false ) . ' /> ' .
 				/** This filter is documented in wp-includes/category-template.php */