wp-includes/PHPMailer/PHPMailer.php:1887Check whether a file path is safe, accessible, and readable.
$pathstringbool protected static function fileIsAccessible($path) { if (!static::isPermittedPath($path)) { return false; } $readable = is_file($path); //If not a UNC path (expected to start with \\), check read permission, see #2069 if (strpos($path, '\\\\') !== 0) { $readable = $readable && is_readable($path); } return $readable; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/PHPMailer.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.