Query: Improve sanitization within WP_Meta_Query.

Merges [52455] to the 5.8 branch.
Props vortfu, xknown, dd32.

git-svn-id: https://develop.svn.wordpress.org/branches/5.8@52461 602fd350-edb4-49c9-b593-d223f7449a82

Author: desrosj

src/wp-includes/class-wp-meta-query.php

@@ -812,7 +812,7 @@ protected function find_compatible_table_alias( $clause, $parent_query ) {
 			$clause_compare  = strtoupper( $clause['compare'] );
 			$sibling_compare = strtoupper( $sibling['compare'] );
 			if ( in_array( $clause_compare, $compatible_compares, true ) && in_array( $sibling_compare, $compatible_compares, true ) ) {
-				$alias = $sibling['alias'];
+				$alias = preg_replace( '/\W/', '_', $sibling['alias'] );
 				break;
 			}
 		}

src/wp-includes/class-wp-tax-query.php

@@ -527,7 +527,7 @@ protected function find_compatible_table_alias( $clause, $parent_query ) {
 
 			// The sibling must both have compatible operator to share its alias.
 			if ( in_array( strtoupper( $sibling['operator'] ), $compatible_operators, true ) ) {
-				$alias = $sibling['alias'];
+				$alias = preg_replace( '/\W/', '_', $sibling['alias'] );
 				break;
 			}
 		}