diff --git a/src/wp-includes/class-walker-category.php b/src/wp-includes/class-walker-category.php
index da518c9ee1..8ef3c58d52 100644
--- a/src/wp-includes/class-walker-category.php
+++ b/src/wp-includes/class-walker-category.php
@@ -170,6 +170,13 @@ class Walker_Category extends Walker {
 					} elseif ( $category->term_id == $_current_term->parent ) {
 						$css_classes[] = 'current-cat-parent';
 					}
+					while ( $_current_term->parent ) {
+						if ( $category->term_id == $_current_term->parent ) {
+							$css_classes[] =  'current-cat-ancestor';
+							break;
+						}
+						$_current_term = get_term( $_current_term->parent, $category->taxonomy );
+					}
 				}
 			}
 
diff --git a/tests/phpunit/tests/category/wpListCategories.php b/tests/phpunit/tests/category/wpListCategories.php
index dad221f7e7..061496a8a6 100644
--- a/tests/phpunit/tests/category/wpListCategories.php
+++ b/tests/phpunit/tests/category/wpListCategories.php
@@ -381,4 +381,25 @@ class Tests_Category_WpListCategories extends WP_UnitTestCase {
 		$this->assertNotContains( '<li class="cat-item cat-item-' . $child3 . '">', $actual );
 		$this->assertNotContains( '<li class="cat-item cat-item-' . $child4 . '">', $actual );
 	}
+
+	/**
+	 * @ticket 10676
+	 */
+	public function test_class_containing_current_cat_ancestor() {
+		$parent = self::factory()->category->create( array( 'name' => 'Parent', 'slug' => 'parent' ) );
+		$child = self::factory()->category->create( array( 'name' => 'Child', 'slug' => 'child', 'parent' => $parent ) );
+		$child2 = self::factory()->category->create( array( 'name' => 'Child 2', 'slug' => 'child2', 'parent' => $parent ) );
+		$grandchild = self::factory()->category->create( array( 'name' => 'Grand Child', 'slug' => 'child', 'parent' => $child ) );
+
+		$actual = wp_list_categories( array(
+			'echo'             => 0,
+			'hide_empty'       => false,
+			'current_category' => $grandchild,
+		) );
+
+		$this->assertRegExp( '/class="[^"]*cat-item-' . $parent . '[^"]*current-cat-ancestor[^"]*"/', $actual );
+		$this->assertRegExp( '/class="[^"]*cat-item-' . $child . '[^"]*current-cat-ancestor[^"]*"/', $actual );
+		$this->assertNotRegExp( '/class="[^"]*cat-item-' . $grandchild . '[^"]*current-cat-ancestor[^"]*"/', $actual );
+		$this->assertNotRegExp( '/class="[^"]*cat-item-' . $child2 . '[^"]*current-cat-ancestor[^"]*"/', $actual );
+	}
 }