Prevent empty author links in list tables

src/wp-admin/includes/class-wp-media-list-table.php

@@ -503,15 +503,22 @@ public function column_title( $post ) {
 	 * Handles the author column output.
 	 *
 	 * @since 4.3.0
+	 * @since 6.8.0 Added fallback text for attachments that have no author.
 	 *
 	 * @param WP_Post $post The current WP_Post object.
 	 */
 	public function column_author( $post ) {
-		printf(
-			'<a href="%s">%s</a>',
-			esc_url( add_query_arg( array( 'author' => get_the_author_meta( 'ID' ) ), 'upload.php' ) ),
-			get_the_author()
-		);
+		$author = get_the_author();
+
+		if ( ! empty( $author ) ) {
+			printf(
+				'<a href="%s">%s</a>',
+				esc_url( add_query_arg( array( 'author' => get_the_author_meta( 'ID' ) ), 'upload.php' ) ),
+				esc_html( $author )
+			);
+		} else {
+			echo '<span aria-hidden="true">&#8212;</span><span class="screen-reader-text">' . __( '(no author)' ) . '</span>';
+		}
 	}
 
 	/**

tests/phpunit/tests/admin/wpMediaListTable.php

@@ -109,6 +109,51 @@ public function tear_down() {
 		parent::tear_down();
 	}
 
+	/**
+	 * Tests that column_author() displays the correct author link when an author exists.
+	 *
+	 * @ticket 62913
+	 * @covers WP_Media_List_Table::column_author
+	 */
+	public function test_column_author_with_valid_author() {
+		wp_set_current_user( self::$admin );
+
+		$author_id = self::factory()->user->create( array( 'role' => 'author' ) );
+		$post      = self::factory()->post->create_and_get( array( 'post_author' => $author_id ) );
+
+		$author_name  = get_the_author_meta( 'display_name', $author_id );
+		$expected_url = esc_url( add_query_arg( array( 'author' => $author_id ), 'upload.php' ) );
+
+		ob_start();
+		self::$list_table->column_author( $post );
+		$output = ob_get_clean();
+
+		$this->assertStringContainsString( '<a href="' . $expected_url . '">', $output );
+		$this->assertStringContainsString( '>' . esc_html( $author_name ) . '</a>', $output );
+	}
+
+	/**
+	 * Tests that column_author() displays the correct fallback when no author exists.
+	 *
+	 * @ticket 62913
+	 * @covers WP_Media_List_Table::column_author
+	 */
+	public function test_column_author_with_no_author() {
+		wp_set_current_user( self::$admin );
+
+		// Create an attachment post with no author (post_author set to 0).
+		$post_id = self::factory()->attachment->create( array( 'post_author' => 0 ) );
+		$post    = get_post( $post_id );
+
+		ob_start();
+		self::$list_table->column_author( $post );
+		$output = ob_get_clean();
+
+		$this->assertStringContainsString( '<span aria-hidden="true">&#8212;</span>', $output );
+		$this->assertStringContainsString( '<span class="screen-reader-text">(no author)</span>', $output );
+		$this->assertStringNotContainsString( '<a href="', $output );
+	}
+
 	/**
 	 * Tests that a call to WP_Media_List_Table::prepare_items() on a site without any scheduled events
 	 * does not result in a PHP warning.