Don't trust properties at destruct time

lib/classes/Swift/ByteStream/TemporaryFileByteStream.php

@@ -39,4 +39,14 @@ public function __destruct()
             @unlink($this->getPath());
         }
     }
+
+    public function __sleep()
+    {
+        throw new \BadMethodCallException('Cannot serialize '.__CLASS__);
+    }
+
+    public function __wakeup()
+    {
+        throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
+    }
 }

lib/classes/Swift/KeyCache/DiskKeyCache.php

@@ -286,4 +286,9 @@ public function __destruct()
             $this->clearAll($nsKey);
         }
     }
+
+    public function __wakeup()
+    {
+        $this->keys = [];
+    }
 }

lib/classes/Swift/Mime/SimpleMimeEntity.php

@@ -817,4 +817,10 @@ public function __clone()
         }
         $this->setChildren($children);
     }
+
+    public function __wakeup()
+    {
+        $this->cacheKey = bin2hex(random_bytes(16)); // set 32 hex values
+        $this->cache = new Swift_KeyCache_ArrayKeyCache(new Swift_KeyCache_SimpleKeyCacheInputStream());
+    }
 }

lib/classes/Swift/Transport/AbstractSmtpTransport.php

@@ -543,4 +543,14 @@ public function __destruct()
         } catch (Exception $e) {
         }
     }
+
+    public function __sleep()
+    {
+        throw new \BadMethodCallException('Cannot serialize '.__CLASS__);
+    }
+
+    public function __wakeup()
+    {
+        throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
+    }
 }