WordPress · Jiwoon-Kim · Sep 17, 2026
diff --git a/src/js/_enqueues/wp/emoji.js b/src/js/_enqueues/wp/emoji.js
@@ -235,9 +235,18 @@
 							return false;
 					}
 
+					/*
+					 * When only the flag test failed, replace flags and nothing else. The list covers
+					 * every kind of flag that test checks (country, subdivision and ZWJ flags), so a
+					 * failing flag is never left to a font that cannot draw it.
+					 */
 					if ( settings.supports.everythingExceptFlag &&
-						! /^1f1(?:e[6-9a-f]|f[0-9a-f])-1f1(?:e[6-9a-f]|f[0-9a-f])$/.test( icon ) && // Country flags.
-						! /^(1f3f3-fe0f-200d-1f308|1f3f4-200d-2620-fe0f)$/.test( icon )             // Rainbow and pirate flags.
+						// Country flags.
+						! /^1f1(?:e[6-9a-f]|f[0-9a-f])-1f1(?:e[6-9a-f]|f[0-9a-f])$/.test( icon ) &&
+						// Subdivision flags, such as England: a black flag, tag characters, and a cancel tag.
+						! /^1f3f4(?:-e00[2-7][0-9a-f])+-e007f$/.test( icon ) &&
+						// Rainbow, transgender and pirate flags.
+						! /^(1f3f3-fe0f-200d-1f308|1f3f3-fe0f-200d-26a7-fe0f|1f3f4-200d-2620-fe0f)$/.test( icon )
 					) {
 						return false;
 					}

diff --git a/tests/qunit/wp-includes/js/emoji-flags.html b/tests/qunit/wp-includes/js/emoji-flags.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html>
+	<head>
+		<title>wp.emoji flag fallback QUnit Test Suite</title>
+		<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+
+		<!-- QUnit -->
+		<link rel="stylesheet" href="../../../../node_modules/qunit/qunit/qunit.css" type="text/css" media="screen" />
+		<script src="../../../../node_modules/qunit/qunit/qunit.js"></script>
+	</head>
+	<body>
+		<div id="qunit"></div>
+		<div id="qunit-fixture"></div>
+
+		<script src="../../../../build/wp-includes/js/twemoji.js"></script>
+		<script>
+			// The state after a browser passes the emoji test and fails only the flag test.
+			window._wpemojiSettings = {
+				baseUrl: 'https://s.w.org/images/core/emoji/17.0.2/72x72/',
+				ext: '.png',
+				svgUrl: 'https://s.w.org/images/core/emoji/17.0.2/svg/',
+				svgExt: '.svg',
+				supports: {
+					flag: false,
+					emoji: true,
+					everything: false,
+					everythingExceptFlag: true
+				}
+			};
+		</script>
+		<script src="../../../../build/wp-includes/js/wp-emoji.js"></script>
+		<script src="emoji-flags.js"></script>
+	</body>
+</html>
diff --git a/tests/qunit/wp-includes/js/emoji-flags.js b/tests/qunit/wp-includes/js/emoji-flags.js
@@ -0,0 +1,78 @@
+( function( QUnit ) {
+	/*
+	 * wp-emoji.js is loaded with `everythingExceptFlag`: the browser renders emoji but failed the
+	 * flag test. Every kind of flag that test checks must then be replaced by an image, and nothing
+	 * else. See https://core.trac.wordpress.org/ticket/63451.
+	 */
+	QUnit.module( 'wp.emoji flag fallback' );
+
+	function imageSources( html ) {
+		var container = document.createElement( 'div' );
+
+		container.innerHTML = html;
+		return Array.prototype.map.call( container.querySelectorAll( 'img.emoji' ), function( img ) {
+			return img.getAttribute( 'src' );
+		} );
+	}
+
+	QUnit.test( 'replaces a country flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDDF0\uD83C\uDDF7' ) ); // Flag: South Korea.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f1f0-1f1f7\.(svg|png)$/.test( sources[0] ), 'for 1f1f0-1f1f7' );
+	} );
+
+	QUnit.test( 'replaces the England flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDFF4\uDB40\uDC67\uDB40\uDC62\uDB40\uDC65\uDB40\uDC6E\uDB40\uDC67\uDB40\uDC7F' ) ); // Flag: England.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f3f4-e0067-e0062-e0065-e006e-e0067-e007f\.(svg|png)$/.test( sources[0] ), 'for 1f3f4-e0067-e0062-e0065-e006e-e0067-e007f' );
+	} );
+
+	QUnit.test( 'replaces the Scotland flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDFF4\uDB40\uDC67\uDB40\uDC62\uDB40\uDC73\uDB40\uDC63\uDB40\uDC74\uDB40\uDC7F' ) ); // Flag: Scotland.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f3f4-e0067-e0062-e0073-e0063-e0074-e007f\.(svg|png)$/.test( sources[0] ), 'for 1f3f4-e0067-e0062-e0073-e0063-e0074-e007f' );
+	} );
+
+	QUnit.test( 'replaces the Wales flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDFF4\uDB40\uDC67\uDB40\uDC62\uDB40\uDC77\uDB40\uDC6C\uDB40\uDC73\uDB40\uDC7F' ) ); // Flag: Wales.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f3f4-e0067-e0062-e0077-e006c-e0073-e007f\.(svg|png)$/.test( sources[0] ), 'for 1f3f4-e0067-e0062-e0077-e006c-e0073-e007f' );
+	} );
+
+	QUnit.test( 'replaces the transgender flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDFF3\uFE0F\u200D\u26A7\uFE0F' ) ); // Transgender flag.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f3f3-fe0f-200d-26a7-fe0f\.(svg|png)$/.test( sources[0] ), 'for 1f3f3-fe0f-200d-26a7-fe0f' );
+	} );
+
+	QUnit.test( 'replaces the rainbow flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDFF3\uFE0F\u200D\uD83C\uDF08' ) ); // Rainbow flag.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f3f3-fe0f-200d-1f308\.(svg|png)$/.test( sources[0] ), 'for 1f3f3-fe0f-200d-1f308' );
+	} );
+
+	QUnit.test( 'replaces the pirate flag', function( assert ) {
+		var sources = imageSources( window.wp.emoji.parse( '\uD83C\uDFF4\u200D\u2620\uFE0F' ) ); // Pirate flag.
+
+		assert.strictEqual( sources.length, 1, 'one image' );
+		assert.ok( /\/1f3f4-200d-2620-fe0f\.(svg|png)$/.test( sources[0] ), 'for 1f3f4-200d-2620-fe0f' );
+	} );
+
+	QUnit.test( 'leaves an emoji that is not a flag as text', function( assert ) {
+		var text = '\uD83D\uDE00'; // Grinning face.
+
+		assert.strictEqual( window.wp.emoji.parse( text ), text );
+	} );
+
+	QUnit.test( 'leaves a black flag on its own as text', function( assert ) {
+		var text = '\uD83C\uDFF4'; // Black flag.
+
+		assert.strictEqual( window.wp.emoji.parse( text ), text );
+	} );
+} )( window.QUnit );