Commit 6b0edddb54 for wordpress.org

commit 6b0edddb54102e991d9d5af1e6759fdb7e310600
Author: Weston Ruter <weston@xwp.co>
Date:   Mon Feb 2 06:14:44 2026 +0000

    Customize: Use `wp_check_filetype()` instead of `substr()` to extract file extension.

    This fixes compatibility with image files that have 4-character extensions, such as `.webp` and `.avif`.

    Follow-up to [57524], [50810], [30309].

    Props buutqn, westonruter.
    See #51228, #35725, #21483.
    Fixes #64557.

    Built from https://develop.svn.wordpress.org/trunk@61576


    git-svn-id: http://core.svn.wordpress.org/trunk@60887 1a063a9b-81f0-0310-95a4-ce76da25c4cd

diff --git a/wp-includes/customize/class-wp-customize-media-control.php b/wp-includes/customize/class-wp-customize-media-control.php
index af137512c4..40d644ca84 100644
--- a/wp-includes/customize/class-wp-customize-media-control.php
+++ b/wp-includes/customize/class-wp-customize-media-control.php
@@ -92,8 +92,9 @@ class WP_Customize_Media_Control extends WP_Customize_Control {
 				 * Fake an attachment model - needs all fields used by template.
 				 * Note that the default value must be a URL, NOT an attachment ID.
 				 */
-				$ext  = substr( $this->setting->default, -3 );
-				$type = in_array( $ext, array( 'jpg', 'png', 'gif', 'bmp', 'webp', 'avif' ), true ) ? 'image' : 'document';
+				$ext       = wp_check_filetype( $this->setting->default )['ext'];
+				$ext_types = wp_get_ext_types();
+				$type      = isset( $ext_types['image'] ) && in_array( $ext, $ext_types['image'], true ) ? 'image' : 'document';

 				$default_attachment = array(
 					'id'    => 1,
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 9b60d8c058..ac0201e095 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '7.0-alpha-61575';
+$wp_version = '7.0-alpha-61576';

 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.