Smarty: Symlink path traversal out of trusted directories

Smarty is a template engine for PHP, facilitating the separation of presentation (HTML/CSS) from application logic. Prior to 5.8.2 (and 4.5.7 on the 4.x line), Security::_checkDir() does not fully resolve symbolic links before validating that a requested path lies within a configured secure directory. An attacker able to place or reference a symlink within a directory Smarty treats as trusted (e.g., a template or config directory) could use it to point outside the intended secure directory, bypassing the containment check and reading arbitrary files accessible to the PHP process. This issue is fixed in versions 5.8.2 and 4.5.7.