Source code snippet from vulnerable script "like.php":
-----------------[ source code start ]---------------------------------
protected function _unsubscribe()
{
/* Fetch data */
$key = trim( IPSText::base64_decode_urlSafe( $this->request['key'] ) );

list( $app, $area, $relId, $likeMemberId, $memberId, $email ) = explode( ';', $key );

/* Member? */
if ( ! $this->memberData['member_id'] )
{
$this->registry->output->showError( 'no_permission', 'pcgl-1' );
}

if ( ! $app || ! $area || ! $relId )
{
$this->registry->output->showError( 'no_permission', 'pcgl-1' );
}

if ( ( $memberId != $likeMemberId ) || ( $memberId != $this->memberData['member_id'] ) )
{
$this->registry->output->showError( 'no_permission', 'pcgl-2' );
}

if ( $email != $this->memberData['email'] )
{
$this->registry->output->showError( 'no_permission', 'pcgl-3' );
}

/* Think we're safe... */
$this->_like = classes_like::bootstrap( $app, $area );
-----------------[ source code end ]-----------------------------------

As seen above, user submitted parameter "key" is first base64 decoded and then
splitted to six variables. After multiple checks function "bootstrap()" is called,
using unvalidated user submitted data for arguments.

Source code snippet from vulnerable script "composite.php":
-----------------[ source code start ]---------------------------------
static public function bootstrap( $app=null, $area=null )
{
...
if( $area != 'default' )
{
$_file = IPSLib::getAppDir( $app ) . '/extensions/like/' . $area . '.php';
...
}
...
if ( ! is_file( $_file ) )
{
...
throw new Exception( "No like class available for $app - $area" );
...
}
...
$classToLoad = IPSLib::loadLibrary( $_file, $_class, $app );
-----------------[ source code end ]-----------------------------------

We can see, that variable "$_file" is composed using unvalidated argument "area".
Next there is check for file existence and in case of success next function,
"loadLibrary", is called, using unvalidated argument "$_file".


Source code snippet from vulnerable script "core.php":
-----------------[ source code start ]---------------------------------
static public function loadLibrary( $filePath, $className, $app='core' )
{
/* Get the class */
if ( $filePath != '' )
{
require_once( $filePath );/*noLibHook*/
}
-----------------[ source code end ]-----------------------------------