CVE-2022-41966

XStream serializes Java objects to XML and back again. Versions prior to 1.4.20 may allow a remote attacker to terminate the application with a stack overflow error, resulting in a denial of service only via manipulation the processed input stream. The attack uses the hash code implementation for collections and maps to force recursive hash calculation causing a stack overflow. This issue is patched in version 1.4.20 which handles the stack overflow and raises an InputManipulationException instead. A potential workaround for users who only use HashMap or HashSet and whose XML refers these only as default map or set, is to change the default implementation of java.util.Map and java.util per the code example in the referenced advisory. However, this implies that your application does not care about the implementation of the map and all elements are comparable.

XStream serializes Java objects to XML and back again. Versions prior to 1.4.20 may allow a remote attacker to terminate the application with a stack overflow error, resulting in a denial of service only via manipulation the processed input stream. The attack uses the hash code implementation for collections and maps to force recursive hash calculation causing a stack overflow. This issue is patched in version 1.4.20 which handles the stack overflow and raises an InputManipulationException instead. A potential workaround for users who only use HashMap or HashSet and whose XML refers these only as default map or set, is to change the default implementation of java.util.Map and java.util per the code example in the referenced advisory. However, this implies that your application does not care about the implementation of the map and all elements are comparable.

### Impact The vulnerability may allow a remote attacker to terminate the application with a stack overflow error resulting in a denial of service only by manipulating the processed input stream. ### Patches XStream 1.4.20 handles the stack overflow and raises an InputManipulationException instead. ### Workarounds The attack uses the hash code implementation for collections and maps to force recursive hash calculation causing a stack overflow. Following types of the Java runtime are affected: - java.util.HashMap - java.util.HashSet - java.util.Hashtable - java.util.LinkedHashMap - java.util.LinkedHashSet - Other third party collection implementations that use their element's hash code may also be affected A simple solution is to catch the StackOverflowError in the client code calling XStream. If your object graph does not use referenced elements at all, you may simply set the NO_REFERENCE mode: ```Java XStream xstream = new XStream(); xstream.setMode(XStream.NO_REFERENCES); ``` If your object graph contains neither a Hashtable, HashMap nor a HashSet (or one of the linked variants of it) then you can use the security framework to deny the usage of these types: ```Java XStream xstream = new XStream(); xstream.denyTypes(new Class[]{ java.util.HashMap.class, java.util.HashSet.class, java.util.Hashtable.class, java.util.LinkedHashMap.class, java.util.LinkedHashSet.class }); ``` Unfortunately these types are very common. If you only use HashMap or HashSet and your XML refers these only as default map or set, you may additionally change the default implementation of java.util.Map and java.util.Set at unmarshalling time:: ```Java xstream.addDefaultImplementation(java.util.TreeMap.class, java.util.Map.class); xstream.addDefaultImplementation(java.util.TreeSet.class, java.util.Set.class); ``` However, this implies that your application does not care about the implementation of the map and all elements are comparable. ### References See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for [CVE-2022-41966](https://x-stream.github.io/CVE-2022-41966.html). ### For more information If you have any questions or comments about this advisory: * Open an issue in [XStream](https://github.com/x-stream/xstream/issues) * Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)

### Impact The vulnerability may allow a remote attacker to terminate the application with a stack overflow error resulting in a denial of service only by manipulating the processed input stream. ### Patches XStream 1.4.20 handles the stack overflow and raises an InputManipulationException instead. ### Workarounds The attack uses the hash code implementation for collections and maps to force recursive hash calculation causing a stack overflow. Following types of the Java runtime are affected: - java.util.HashMap - java.util.HashSet - java.util.Hashtable - java.util.LinkedHashMap - java.util.LinkedHashSet - Other third party collection implementations that use their element's hash code may also be affected A simple solution is to catch the StackOverflowError in the client code calling XStream. If your object graph does not use referenced elements at all, you may simply set the NO_REFERENCE mode: ```Java XStream xstream = new XStream(); xstream.setMode(XStream.NO_REFERENCES); ``` If your object graph contains neither a Hashtable, HashMap nor a HashSet (or one of the linked variants of it) then you can use the security framework to deny the usage of these types: ```Java XStream xstream = new XStream(); xstream.denyTypes(new Class[]{ java.util.HashMap.class, java.util.HashSet.class, java.util.Hashtable.class, java.util.LinkedHashMap.class, java.util.LinkedHashSet.class }); ``` Unfortunately these types are very common. If you only use HashMap or HashSet and your XML refers these only as default map or set, you may additionally change the default implementation of java.util.Map and java.util.Set at unmarshalling time:: ```Java xstream.addDefaultImplementation(java.util.TreeMap.class, java.util.Map.class); xstream.addDefaultImplementation(java.util.TreeSet.class, java.util.Set.class); ``` However, this implies that your application does not care about the implementation of the map and all elements are comparable. ### References See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for [CVE-2022-41966](https://x-stream.github.io/CVE-2022-41966.html). ### For more information If you have any questions or comments about this advisory: * Open an issue in [XStream](https://github.com/x-stream/xstream/issues) * Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)

XStream serializa objetos Java a XML y viceversa. Las versiones anteriores a la 1.4.20 pueden permitir que un atacante remoto finalice la aplicación con un error de desbordamiento de pila, lo que resulta en una denegación de servicio únicamente mediante la manipulación del flujo de entrada procesado. El ataque utiliza la implementación del código hash para colecciones y mapas para forzar el cálculo hash recursivo provocando un desbordamiento de la pila. Este problema se solucionó en la versión 1.4.20, que maneja el desbordamiento de la pila y genera una excepción InputManipulationException. Una posible solución para los usuarios que solo usan HashMap o HashSet y cuyo XML los refiere solo como mapa o conjunto predeterminado, es cambiar la implementación predeterminada de java.util.Map y java.util según el ejemplo de código en el aviso al que se hace referencia. Sin embargo, esto implica que a su aplicación no le importa la implementación del mapa y todos los elementos son comparables.