diff --git a/src/wp-includes/class-wp-icons-registry.php b/src/wp-includes/class-wp-icons-registry.php
index a10960da9a077..6d7ac0e0de689 100644
--- a/src/wp-includes/class-wp-icons-registry.php
+++ b/src/wp-includes/class-wp-icons-registry.php
@@ -237,29 +237,53 @@ public function unregister( $icon_name ) {
 	 * @return string The sanitized icon SVG content.
 	 */
 	protected function sanitize_icon_content( $icon_content ) {
+		$stroke_attributes = array(
+			'style'             => true,
+			'stroke'            => true,
+			'stroke-width'      => true,
+			'stroke-linecap'    => true,
+			'stroke-linejoin'   => true,
+			'stroke-miterlimit' => true,
+			'vector-effect'     => true,
+		);
+
 		$allowed_tags = array(
-			'svg'     => array(
-				'class'       => true,
-				'xmlns'       => true,
-				'width'       => true,
-				'height'      => true,
-				'viewbox'     => true,
-				'aria-hidden' => true,
-				'role'        => true,
-				'focusable'   => true,
+			'svg'     => array_merge(
+				array(
+					'class'       => true,
+					'xmlns'       => true,
+					'width'       => true,
+					'height'      => true,
+					'viewbox'     => true,
+					'aria-hidden' => true,
+					'role'        => true,
+					'focusable'   => true,
+					'fill'        => true,
+					'fill-rule'   => true,
+					'clip-rule'   => true,
+				),
+				$stroke_attributes
 			),
-			'path'    => array(
-				'fill'      => true,
-				'fill-rule' => true,
-				'd'         => true,
-				'transform' => true,
+			'path'    => array_merge(
+				array(
+					'fill'      => true,
+					'fill-rule' => true,
+					'clip-rule' => true,
+					'd'         => true,
+					'transform' => true,
+				),
+				$stroke_attributes
 			),
-			'polygon' => array(
-				'fill'      => true,
-				'fill-rule' => true,
-				'points'    => true,
-				'transform' => true,
-				'focusable' => true,
+			'polygon' => array_merge(
+				array(
+					'fill'      => true,
+					'fill-rule' => true,
+					'clip-rule' => true,
+					'points'    => true,
+					'transform' => true,
+					'focusable' => true,
+				),
+				$stroke_attributes
 			),
 		);
 		return wp_kses( $icon_content, $allowed_tags );
diff --git a/tests/phpunit/tests/icons/wpIconsRegistry.php b/tests/phpunit/tests/icons/wpIconsRegistry.php
index 42853d2666a95..c6268666a2b7f 100644
--- a/tests/phpunit/tests/icons/wpIconsRegistry.php
+++ b/tests/phpunit/tests/icons/wpIconsRegistry.php
@@ -284,6 +284,70 @@ public function test_register_icon_sanitizes_content() {
 		$this->assertSame( '<svg viewbox="0 0 24 24"><path d="M0 0" /></svg>', $icon['content'] );
 	}
 
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_icon_content_sources() {
+		return array(
+			'inline content' => array( false ),
+			'file path'      => array( true ),
+		);
+	}
+
+	/**
+	 * Should preserve the attributes that stroke-based icons rely on.
+	 *
+	 * Only covers the attributes allowed for stroke-based icons. Those that were
+	 * already allowed are covered by test_register_icon_sanitizes_content().
+	 *
+	 * @ticket 66101
+	 *
+	 * @dataProvider data_icon_content_sources
+	 *
+	 * @covers ::register
+	 *
+	 * @param bool $use_file_path Whether to register the icon from a file path.
+	 */
+	public function test_register_icon_preserves_stroke_attributes( $use_file_path ) {
+		$stroke   = 'style="fill: none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" stroke-miterlimit="10" vector-effect="non-scaling-stroke"';
+		$content  = '<svg fill="currentColor" fill-rule="evenodd" clip-rule="evenodd" ' . $stroke . '>' .
+			'<path clip-rule="evenodd" ' . $stroke . ' />' .
+			'<polygon clip-rule="evenodd" ' . $stroke . ' />' .
+			'</svg>';
+		$name     = 'test-collection/stroke-icon';
+		$settings = array( 'label' => 'Stroke Icon' );
+
+		if ( $use_file_path ) {
+			$settings['file_path'] = $this->create_temp_icon_file( $content );
+		} else {
+			$settings['content'] = $content;
+		}
+
+		$this->assertTrue( $this->registry->register( $name, $settings ) );
+
+		$icon = $this->registry->get_registered_icon( $name );
+
+		$this->assertStringContainsString(
+			'<svg fill="currentColor" fill-rule="evenodd" clip-rule="evenodd" ' . $stroke . '>',
+			$icon['content'],
+			'Attributes were altered or stripped from the svg element.'
+		);
+
+		$this->assertStringContainsString(
+			'<path clip-rule="evenodd" ' . $stroke . ' />',
+			$icon['content'],
+			'Attributes were altered or stripped from the path element.'
+		);
+
+		$this->assertStringContainsString(
+			'<polygon clip-rule="evenodd" ' . $stroke . ' />',
+			$icon['content'],
+			'Attributes were altered or stripped from the polygon element.'
+		);
+	}
+
 	/**
 	 * Should fail to register an icon that provides both `content` and `file_path`.
 	 *