diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-includes/class-wpdb.php
--- a/wp/wp-includes/class-wpdb.php	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-includes/class-wpdb.php	Fri Sep 05 18:52:52 2025 +0200
@@ -749,7 +749,13 @@
 	 * @param string $dbname     Database name.
 	 * @param string $dbhost     Database host.
 	 */
-	public function __construct( $dbuser, $dbpassword, $dbname, $dbhost ) {
+	public function __construct(
+		$dbuser,
+		#[\SensitiveParameter]
+		$dbpassword,
+		$dbname,
+		$dbhost
+	) {
 		if ( WP_DEBUG && WP_DEBUG_DISPLAY ) {
 			$this->show_errors();
 		}
@@ -2114,7 +2120,8 @@
 	 * @return bool|void True if the connection is up.
 	 */
 	public function check_connection( $allow_bail = true ) {
-		if ( ! empty( $this->dbh ) && mysqli_ping( $this->dbh ) ) {
+		// Check if the connection is alive.
+		if ( ! empty( $this->dbh ) && mysqli_query( $this->dbh, 'DO 1' ) !== false ) {
 			return true;
 		}
 
@@ -2405,12 +2412,10 @@
 		static $placeholder;
 
 		if ( ! $placeholder ) {
-			// If ext/hash is not present, compat.php's hash_hmac() does not support sha256.
-			$algo = function_exists( 'hash' ) ? 'sha256' : 'sha1';
 			// Old WP installs may not have AUTH_SALT defined.
 			$salt = defined( 'AUTH_SALT' ) && AUTH_SALT ? AUTH_SALT : (string) rand();
 
-			$placeholder = '{' . hash_hmac( $algo, uniqid( $salt, true ), $salt ) . '}';
+			$placeholder = '{' . hash_hmac( 'sha256', uniqid( $salt, true ), $salt ) . '}';
 		}
 
 		/*
@@ -3982,12 +3987,13 @@
 	 *
 	 * @since 2.5.0
 	 *
-	 * @global string $wp_version             The WordPress version string.
 	 * @global string $required_mysql_version The required MySQL version string.
 	 * @return void|WP_Error
 	 */
 	public function check_database_version() {
-		global $wp_version, $required_mysql_version;
+		global $required_mysql_version;
+		$wp_version = wp_get_wp_version();
+
 		// Make sure the server has the required MySQL version.
 		if ( version_compare( $this->db_version(), $required_mysql_version, '<' ) ) {
 			/* translators: 1: WordPress version number, 2: Minimum required MySQL version number. */