Is this preg_replace example exploitable in any way?

Question

Is this code explotable in any way?

<?
$arg=$_REQUEST['arg'];
preg_replace("/([0-9]+)(.+)/e",'list($var,$var2)=array("$1","$2")',$arg);
echo "$var - $var2";
?>

Is it possible to use special characters or some other method to inject code?

I'm using similar code in some projects and I just want to make sure that it is safe.

Answer 1

Using

(.+)

with /e parameter is always exploitable because it allows any language constructions there.

Example exploit code:

$test = new test();
$test->setSuperSecret();
$test->exploitableExpression();

class test
{
    private $mySuperSecretVariable;
    public function exploitableExpression()
    {
        $arg= '1234$this->mySuperSecretVariable';
        preg_replace("/([0-9]+)(.+)/e",'list($var,$var2)=array("$1","$2")',$arg);
        var_dump($var,$var2);
    }
    public function setSuperSecret()
    {
        $this->mySuperSecretVariable = 'SECRET!';
    }
}