Index: wp-admin/includes/post-formats.php
===================================================================
--- wp-admin/includes/post-formats.php	(revision 23868)
+++ wp-admin/includes/post-formats.php	(working copy)
@@ -37,7 +37,7 @@
 			</a>
 		</div>
 		<label for="_wp_format_image" class="screen-reader-text"><?php _e( 'Image URL' ); ?>:</label>
-		<input id="wp_format_image" type="hidden" name="_wp_format_image" value="<?php echo esc_url( $format_meta['image'] ); ?>" placeholder="<?php esc_attr_e( 'Image URL' ); ?>" class="widefat" />
+		<input id="wp_format_image" type="hidden" name="_wp_format_image" value="<?php echo absint( $format_meta['image'] ); ?>" placeholder="<?php esc_attr_e( 'Image URL' ); ?>" class="widefat" />
 	</div>
 
 	<div class="field wp-format-link wp-format-quote wp-format-image">