diff --git a/wp-activate.php b/wp-activate.php
index 5dc602337b..f4fd8d76c3 100644
--- a/wp-activate.php
+++ b/wp-activate.php
@@ -29,9 +29,9 @@ $result = null;
 if ( isset( $_GET['key'] ) && isset( $_POST['key'] ) && $_GET['key'] !== $_POST['key'] ) {
 	wp_die( __( 'A key value mismatch has been detected. Please follow the link provided in your activation email.' ), __( 'An error occurred during the activation' ), 400 );
 } elseif ( ! empty( $_GET['key'] ) ) {
-	$key = $_GET['key'];
+	$key = sanitize_text_field( $_GET['key'] );
 } elseif ( ! empty( $_POST['key'] ) ) {
-	$key = $_POST['key'];
+	$key = sanitize_text_field( $_POST['key'] );
 }
 
 if ( $key ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index a455ed50bf..cbc3209f08 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.9-alpha-60203';
+$wp_version = '6.9-alpha-60204';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.