If the certificate arrays happen to be sparsely indexed this can blow out the memory.

One scenario is indexing the certificates based on the short hash, php
will magically expand this hex string in to a very large index number.
eg,
 'd5c242d7' => '-----BEGIN CERTIFICATE-----...'
will cause loop to go from i=0 to i=3586278103

Author: Andrew Thompson

lib/Saml2/Settings.php

@@ -941,13 +941,13 @@ public function formatIdPCertMulti()
     {
         if (isset($this->_idp['x509certMulti'])) {
             if (isset($this->_idp['x509certMulti']['signing'])) {
-                for ($i=0; $i < count($this->_idp['x509certMulti']['signing']); $i++) {
-                    $this->_idp['x509certMulti']['signing'][$i] = OneLogin_Saml2_Utils::formatCert($this->_idp['x509certMulti']['signing'][$i]);
+                foreach($this->_idp['x509certMulti']['signing'] as $i => $cert) {
+                    $this->_idp['x509certMulti']['signing'][$i] = OneLogin_Saml2_Utils::formatCert($cert);
                 }
             }
             if (isset($this->_idp['x509certMulti']['encryption'])) {
-                for ($i=0; $i < count($this->_idp['x509certMulti']['encryption']); $i++) {
-                    $this->_idp['x509certMulti']['encryption'][$i] = OneLogin_Saml2_Utils::formatCert($this->_idp['x509certMulti']['encryption'][$i]);
+                foreach($this->_idp['x509certMulti']['encryption'] as $i => $cert) {
+                    $this->_idp['x509certMulti']['encryption'][$i] = OneLogin_Saml2_Utils::formatCert($cert);
                 }
             }
         }