diff --git a/src/wp-admin/includes/class-wp-plugins-list-table.php b/src/wp-admin/includes/class-wp-plugins-list-table.php
index 08b2e982e702f..7f63a99dd30d7 100644
--- a/src/wp-admin/includes/class-wp-plugins-list-table.php
+++ b/src/wp-admin/includes/class-wp-plugins-list-table.php
@@ -1365,7 +1365,7 @@ public function single_row( $item ) {
 					if ( $paused ) {
 						$notice_text = __( 'This plugin failed to load properly and is paused during recovery mode.' );
 
-						printf( '<p><span class="dashicons dashicons-warning"></span> <strong>%s</strong></p>', $notice_text );
+						printf( '<p><span class="dashicons dashicons-warning" aria-hidden="true"></span> <strong>%s</strong></p>', $notice_text );
 
 						$error = wp_get_plugin_error( $plugin_file );
 
diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index dca95d69b69fe..1963cc880210e 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -970,7 +970,7 @@ function do_enclose( $content, $post ) {
 				}
 
 				if ( in_array( substr( $type, 0, strpos( $type, '/' ) ), $allowed_types, true ) ) {
-					add_post_meta( $post->ID, 'enclosure', "$url\n$len\n$mime\n" );
+					add_post_meta( $post->ID, 'enclosure', "$url\n$len\n$type\n" );
 				}
 			}
 		}
diff --git a/src/wp-includes/general-template.php b/src/wp-includes/general-template.php
index 29c30137e173d..76fd8ada83b69 100644
--- a/src/wp-includes/general-template.php
+++ b/src/wp-includes/general-template.php
@@ -1878,6 +1878,8 @@ function single_month_title( $prefix = '', $display = true ) {
 	$m        = get_query_var( 'm' );
 	$year     = get_query_var( 'year' );
 	$monthnum = get_query_var( 'monthnum' );
+	$my_year  = '';
+	$my_month = '';
 
 	if ( ! empty( $monthnum ) && ! empty( $year ) ) {
 		$my_year  = $year;
@@ -5421,6 +5423,7 @@ function get_the_generator( $type = '' ) {
 				break;
 		}
 	}
+	$gen = '';
 
 	switch ( $type ) {
 		case 'html':
diff --git a/src/wp-includes/html-api/class-wp-html-processor.php b/src/wp-includes/html-api/class-wp-html-processor.php
index b2a597b938495..7de136e5cd696 100644
--- a/src/wp-includes/html-api/class-wp-html-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-processor.php
@@ -3394,6 +3394,7 @@ private function in_body_any_other_end_tag(): bool {
 		 * of boundary in the stack. For example, a `</custom-tag>` should not
 		 * close anything beyond its containing `P` or `DIV` element.
 		 */
+		$node = null;
 		foreach ( $this->state->stack_of_open_elements->walk_up() as $node ) {
 			if ( 'html' === $node->namespace && $token_name === $node->node_name ) {
 				break;
diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 3813176140bb4..34553c98f502e 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -7489,6 +7489,7 @@ function wp_mime_type_icon( $mime = 0, $preferred_ext = '.png' ) {
 		$matches            = wp_match_mime_types( array_keys( $types ), $post_mimes );
 		$matches['default'] = array( 'default' );
 
+		$icon = false;
 		foreach ( $matches as $match => $wilds ) {
 			foreach ( $wilds as $wild ) {
 				if ( ! isset( $types[ $wild ] ) ) {
diff --git a/src/wp-includes/user.php b/src/wp-includes/user.php
index d682762acb7e7..19a3ce2fcf4db 100644
--- a/src/wp-includes/user.php
+++ b/src/wp-includes/user.php
@@ -4275,6 +4275,7 @@ function _wp_privacy_send_request_confirmation_notification( $request_id ) {
 		return;
 	}
 
+	$manage_url = '';
 	if ( 'export_personal_data' === $request->action_name ) {
 		$manage_url = admin_url( 'export-personal-data.php' );
 	} elseif ( 'remove_personal_data' === $request->action_name ) {
diff --git a/tests/phpunit/tests/functions/doEnclose.php b/tests/phpunit/tests/functions/doEnclose.php
index 6d36fd373a779..a0a4ca7c48589 100644
--- a/tests/phpunit/tests/functions/doEnclose.php
+++ b/tests/phpunit/tests/functions/doEnclose.php
@@ -125,6 +125,10 @@ public function data_do_enclose() {
 				'content'  => 'https://example.com?test=1',
 				'expected' => '',
 			),
+			'header-type-no-extension' => array(
+				'content'  => 'https://example.com/media/stream-mp4',
+				'expected' => "https://example.com/media/stream-mp4\n123\nvideo/mp4\n",
+			),
 		);
 	}
 
@@ -276,6 +280,9 @@ public function mock_http_request( $response, $parsed_args, $url ) {
 		$path = parse_url( $url, PHP_URL_PATH );
 
 		if ( is_string( $path ) ) {
+			if ( str_contains( $path, 'stream-mp4' ) ) {
+				return $fake_headers['mp4'];
+			}
 			$extension = pathinfo( $path, PATHINFO_EXTENSION );
 			if ( isset( $fake_headers[ $extension ] ) ) {
 				return $fake_headers[ $extension ];