Ticket #20074: 20074.4.diff

src/wp-admin/includes/file.php

@@ -485 +485 @@
                 return new WP_Error( 'http_404', trim( wp_remote_retrieve_response_message( $response ) ) );
         }
 
+        $content_md5 = wp_remote_retrieve_header( $response, 'content-md5' );
+        if ( $content_md5 ) {
+                $md5_file = md5_file( $tmpfname );
+                if ( $md5_file != $content_md5 ) {
+                        unlink( $tmpfname );
+                        return new WP_Error( 'download_verification_failed', sprintf( __( 'The checksum of the download (%1$s) does not match the provided checksum value (%2$s).' ), $md5_file, $content_md5 ) );
+                }
+        }
+
         return $tmpfname;
 }