diff --git a/src/wp-admin/includes/class-wp-debug-data.php b/src/wp-admin/includes/class-wp-debug-data.php
index f2399b30550c9..7a65cdaef7979 100644
--- a/src/wp-admin/includes/class-wp-debug-data.php
+++ b/src/wp-admin/includes/class-wp-debug-data.php
@@ -472,74 +472,83 @@ private static function get_wp_server(): array {
 		);
 
 		// Opcode Cache.
-		if ( function_exists( 'opcache_get_status' ) ) {
-			$opcache_status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
-
-			if ( false === $opcache_status ) {
-				$fields['opcode_cache'] = array(
-					'label' => __( 'Opcode cache' ),
-					'value' => __( 'Disabled by configuration' ),
-					'debug' => 'not available',
-				);
-			} else {
-				$fields['opcode_cache'] = array(
-					'label' => __( 'Opcode cache' ),
-					'value' => $opcache_status['opcache_enabled'] ? __( 'Enabled' ) : __( 'Disabled' ),
-					'debug' => $opcache_status['opcache_enabled'],
+		// Only query opcache_get_status() when the genuine Zend OPcache extension
+		// is loaded, so a userland opcache_get_status() polyfill cannot spoof the
+		// reported status.
+		$opcache_status = ( extension_loaded( 'Zend OPcache' ) && function_exists( 'opcache_get_status' ) )
+			? @opcache_get_status( false ) // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
+			: false;
+
+		if ( is_array( $opcache_status ) ) {
+			$fields['opcode_cache'] = array(
+				'label' => __( 'Opcode cache' ),
+				'value' => $opcache_status['opcache_enabled'] ? __( 'Enabled' ) : __( 'Disabled' ),
+				'debug' => $opcache_status['opcache_enabled'],
+			);
+
+			if ( true === $opcache_status['opcache_enabled'] ) {
+				$fields['opcode_cache_memory_usage'] = array(
+					'label' => __( 'Opcode cache memory usage' ),
+					'value' => sprintf(
+						/* translators: 1: Used memory, 2: Total memory */
+						__( '%1$s of %2$s' ),
+						size_format( $opcache_status['memory_usage']['used_memory'] ),
+						size_format( $opcache_status['memory_usage']['free_memory'] + $opcache_status['memory_usage']['used_memory'] )
+					),
+					'debug' => sprintf(
+						'%s of %s',
+						$opcache_status['memory_usage']['used_memory'],
+						$opcache_status['memory_usage']['free_memory'] + $opcache_status['memory_usage']['used_memory']
+					),
 				);
 
-				if ( true === $opcache_status['opcache_enabled'] ) {
-					$fields['opcode_cache_memory_usage'] = array(
-						'label' => __( 'Opcode cache memory usage' ),
+				if ( 0 !== $opcache_status['interned_strings_usage']['buffer_size'] ) {
+					$fields['opcode_cache_interned_strings_usage'] = array(
+						'label' => __( 'Opcode cache interned strings usage' ),
 						'value' => sprintf(
-							/* translators: 1: Used memory, 2: Total memory */
-							__( '%1$s of %2$s' ),
-							size_format( $opcache_status['memory_usage']['used_memory'] ),
-							size_format( $opcache_status['memory_usage']['free_memory'] + $opcache_status['memory_usage']['used_memory'] )
+							/* translators: 1: Percentage used, 2: Total memory, 3: Free memory */
+							__( '%1$s%% of %2$s (%3$s free)' ),
+							number_format_i18n( ( $opcache_status['interned_strings_usage']['used_memory'] / $opcache_status['interned_strings_usage']['buffer_size'] ) * 100, 2 ),
+							size_format( $opcache_status['interned_strings_usage']['buffer_size'] ),
+							size_format( $opcache_status['interned_strings_usage']['free_memory'] )
 						),
 						'debug' => sprintf(
-							'%s of %s',
-							$opcache_status['memory_usage']['used_memory'],
-							$opcache_status['memory_usage']['free_memory'] + $opcache_status['memory_usage']['used_memory']
+							'%s%% of %s (%s free)',
+							round( ( $opcache_status['interned_strings_usage']['used_memory'] / $opcache_status['interned_strings_usage']['buffer_size'] ) * 100, 2 ),
+							$opcache_status['interned_strings_usage']['buffer_size'],
+							$opcache_status['interned_strings_usage']['free_memory']
 						),
 					);
+				}
 
-					if ( 0 !== $opcache_status['interned_strings_usage']['buffer_size'] ) {
-						$fields['opcode_cache_interned_strings_usage'] = array(
-							'label' => __( 'Opcode cache interned strings usage' ),
-							'value' => sprintf(
-								/* translators: 1: Percentage used, 2: Total memory, 3: Free memory */
-								__( '%1$s%% of %2$s (%3$s free)' ),
-								number_format_i18n( ( $opcache_status['interned_strings_usage']['used_memory'] / $opcache_status['interned_strings_usage']['buffer_size'] ) * 100, 2 ),
-								size_format( $opcache_status['interned_strings_usage']['buffer_size'] ),
-								size_format( $opcache_status['interned_strings_usage']['free_memory'] )
-							),
-							'debug' => sprintf(
-								'%s%% of %s (%s free)',
-								round( ( $opcache_status['interned_strings_usage']['used_memory'] / $opcache_status['interned_strings_usage']['buffer_size'] ) * 100, 2 ),
-								$opcache_status['interned_strings_usage']['buffer_size'],
-								$opcache_status['interned_strings_usage']['free_memory']
-							),
-						);
-					}
-
-					$fields['opcode_cache_hit_rate'] = array(
-						'label' => __( 'Opcode cache hit rate' ),
-						'value' => sprintf(
-							/* translators: %s: Hit rate percentage */
-							__( '%s%%' ),
-							number_format_i18n( $opcache_status['opcache_statistics']['opcache_hit_rate'], 2 )
-						),
-						'debug' => round( $opcache_status['opcache_statistics']['opcache_hit_rate'], 2 ),
-					);
+				$fields['opcode_cache_hit_rate'] = array(
+					'label' => __( 'Opcode cache hit rate' ),
+					'value' => sprintf(
+						/* translators: %s: Hit rate percentage */
+						__( '%s%%' ),
+						number_format_i18n( $opcache_status['opcache_statistics']['opcache_hit_rate'], 2 )
+					),
+					'debug' => round( $opcache_status['opcache_statistics']['opcache_hit_rate'], 2 ),
+				);
 
-					$fields['opcode_cache_full'] = array(
-						'label' => __( 'Is the Opcode cache full?' ),
-						'value' => $opcache_status['cache_full'] ? __( 'Yes' ) : __( 'No' ),
-						'debug' => $opcache_status['cache_full'],
-					);
-				}
+				$fields['opcode_cache_full'] = array(
+					'label' => __( 'Is the Opcode cache full?' ),
+					'value' => $opcache_status['cache_full'] ? __( 'Yes' ) : __( 'No' ),
+					'debug' => $opcache_status['cache_full'],
+				);
 			}
+		} elseif ( extension_loaded( 'Zend OPcache' ) && ini_get( 'opcache.enable' ) ) {
+			/*
+			 * OPcache is enabled but opcache_get_status() returned no data, for
+			 * example in file cache only mode (opcache.file_cache_only=1) or when the
+			 * function is listed in disable_functions. Detailed statistics are
+			 * unavailable in this case.
+			 */
+			$fields['opcode_cache'] = array(
+				'label' => __( 'Opcode cache' ),
+				'value' => __( 'Enabled' ),
+				'debug' => true,
+			);
 		} else {
 			$fields['opcode_cache'] = array(
 				'label' => __( 'Opcode cache' ),
diff --git a/src/wp-admin/includes/class-wp-site-health.php b/src/wp-admin/includes/class-wp-site-health.php
index 75e046ef8ffa7..e222c5ff2927d 100644
--- a/src/wp-admin/includes/class-wp-site-health.php
+++ b/src/wp-admin/includes/class-wp-site-health.php
@@ -2810,10 +2810,21 @@ public function get_test_search_engine_visibility() {
 	 */
 	public function get_test_opcode_cache(): array {
 		$opcode_cache_enabled = false;
-		if ( function_exists( 'opcache_get_status' ) ) {
-			$status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
-			if ( $status && true === $status['opcache_enabled'] ) {
-				$opcode_cache_enabled = true;
+		if ( extension_loaded( 'Zend OPcache' ) && ini_get( 'opcache.enable' ) ) {
+			/*
+			 * OPcache is enabled. When it operates in file cache only mode
+			 * (opcache.file_cache_only=1), opcache_get_status() returns false
+			 * even though opcode caching is active, so treat the extension being
+			 * enabled as sufficient and only defer to opcache_get_status() when
+			 * it returns usable data.
+			 */
+			$opcode_cache_enabled = true;
+
+			if ( function_exists( 'opcache_get_status' ) ) {
+				$status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
+				if ( is_array( $status ) && isset( $status['opcache_enabled'] ) ) {
+					$opcode_cache_enabled = (bool) $status['opcache_enabled'];
+				}
 			}
 		}
 
diff --git a/tests/phpunit/tests/admin/wpSiteHealth.php b/tests/phpunit/tests/admin/wpSiteHealth.php
index 6080b477f54c3..c0851e6963bc6 100644
--- a/tests/phpunit/tests/admin/wpSiteHealth.php
+++ b/tests/phpunit/tests/admin/wpSiteHealth.php
@@ -681,9 +681,12 @@ public function test_get_test_opcode_cache_return_structure() {
 	/**
 	 * Tests get_test_opcode_cache() result when opcode cache is enabled or not.
 	 *
-	 * Covers: opcache enabled, disabled, not available, and opcache_get_status() returns false.
+	 * Covers: opcache enabled, disabled, not available, file cache only mode
+	 * (where opcache_get_status() returns false), and opcache_get_status()
+	 * being unavailable via disable_functions.
 	 *
 	 * @ticket 63697
+	 * @ticket 64707
 	 *
 	 * @covers ::get_test_opcode_cache()
 	 */
@@ -691,10 +694,14 @@ public function test_get_test_opcode_cache_result_by_environment() {
 		$result = $this->instance->get_test_opcode_cache();
 
 		$opcache_enabled = false;
-		if ( function_exists( 'opcache_get_status' ) ) {
-			$status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
-			if ( $status && true === $status['opcache_enabled'] ) {
-				$opcache_enabled = true;
+		if ( extension_loaded( 'Zend OPcache' ) && ini_get( 'opcache.enable' ) ) {
+			$opcache_enabled = true;
+
+			if ( function_exists( 'opcache_get_status' ) ) {
+				$status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
+				if ( is_array( $status ) && isset( $status['opcache_enabled'] ) ) {
+					$opcache_enabled = (bool) $status['opcache_enabled'];
+				}
 			}
 		}