the term bug may be excessive, however it is possible to easily correct :)

I have a website with more than 700MB image and distributed in 4000 files to 4
levels deep in the directory / upload / Gallery. after an upgrade from 1.9.4.3
to 1.11.4 I met excessive delays leading to regular timeouts on my Hoster in:
ImageManager, FileManager but not in Gallery

After some research in the code I found this:

It exists in the class /lib/ImageManager/Classes/ImageManager.php the function
getDirs() which, in essence, gives a list of existing directories and
subdirectories from a given path to the class that we will call here $PATH

In our case (4 or 5 levels deep, thousands of files) it takes time to explore
everything. This is normal in absolute ...

But there is another feature in this class: validRelativePath(), a function
whose role is to determine whether a relative path passed as parameter is
correct with respect to the $PATH of the class. I would have expected a code
like this:
 * check the existence of the directory
 * a regex control the absence of crappy path (../../../../config.php)
 * control to ensure that the relative path starts well in $ PATH

Nothing complex ... except that the code validRelativePath() uses getDirs() that
suddenly a listing TOTAL existing directories to see if it exists in the list
... Even better it performs this scan painful and returns true if the parameter
is set to '/' ... as saying that the scan is unnecessarily when you're in the
root path

/**
     * Check if the given path is part of the subdirectories
     * under the base_dir.
     * @param string $path the relative path to be checked
     * @return boolean true if the path exists, false otherwise
     */
    function validRelativePath($path)
    {
        $dirs = $this->getDirs();
        if($path == '/' || $path == '\/') return true; // stupid windoze.
        //check the path given in the url against the
        //list of paths in the system.
        for($i = 0; $i < count($dirs); $i++)
        {
            $key = key($dirs);
            //we found the path
            if($key == $path) {
              return true;
            }
       
            next($dirs);
        }
        return false;
    }

And lack of bowl .... validRelativePath() is used everywhere ... even in
ImageManager and FileManager


Now the solution : 

	function validRelativePath($path) 
	{
		return strpos(
			realpath($this->getBaseDir() . DIRECTORY_SEPARATOR . $path), 
			realpath($this->getBaseDir())
		) === 0;
	}

explanation :
http://stackoverflow.com/questions/7545468/regex-to-check-if-a-path-go-only-down

it's secure and instantly returns the result :)