diff --git a/pom.xml b/pom.xml
index 180a0e2..fac1c70 100644
--- a/pom.xml
+++ b/pom.xml
@@ -144,7 +144,7 @@
 			<dependency>
 				<groupId>com.thoughtworks.xstream</groupId>
 				<artifactId>xstream</artifactId>
-				<version>1.4.8</version>
+				<version>1.4.18</version>
 				<exclusions>
 					<exclusion>
 						<artifactId>xmlpull</artifactId>
diff --git a/src/main/java/de/scrum_master/galileo/Book.java b/src/main/java/de/scrum_master/galileo/Book.java
index ee73a17..d625624 100644
--- a/src/main/java/de/scrum_master/galileo/Book.java
+++ b/src/main/java/de/scrum_master/galileo/Book.java
@@ -7,6 +7,7 @@
 import com.thoughtworks.xstream.XStream;
 import com.thoughtworks.xstream.io.xml.DomDriver;
 
+import com.thoughtworks.xstream.security.AnyTypePermission;
 import de.scrum_master.util.SimpleLogger;
 
 public class Book
@@ -23,6 +24,7 @@ public class Book
 	public final static XStream XSTREAM         = new XStream(new DomDriver());
 
 	static {
+		XSTREAM.addPermission(AnyTypePermission.ANY);
 		XSTREAM.alias("galileo-openbooks", TreeMap.class);
 		XSTREAM.alias("book", Book.class);
 		XSTREAM.alias("id", String.class);