CVE Vulnerabilities

CVE-2021-21346

Deserialization of Untrusted Data

Published: Mar 23, 2021 | Modified: Feb 16, 2022
CVSS 3.x
9.8
CRITICAL
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.5 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
8.1 IMPORTANT
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Ubuntu

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability which may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream’s security framework with a whitelist limited to the minimal required types. If you rely on XStream’s default blacklist of the Security Framework, you will have to use at least version 1.4.16.

Weakness

The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

Affected Software

Name Vendor Start Version End Version
Xstream Xstream_project * *
Red Hat Data Grid 8 RedHat xstream *
Red Hat Descision Manager 7 RedHat xstream *
Red Hat Enterprise Linux 7 RedHat xstream-0:1.3.1-13.el7_9 *
Red Hat Integration Camel Quarkus RedHat xstream *
Red Hat JBoss Fuse 7 RedHat xstream *
Red Hat Process Automation 7 RedHat xstream *
Libxstream-java Ubuntu bionic *
Libxstream-java Ubuntu devel *
Libxstream-java Ubuntu focal *
Libxstream-java Ubuntu groovy *
Libxstream-java Ubuntu hirsute *
Libxstream-java Ubuntu impish *
Libxstream-java Ubuntu jammy *
Libxstream-java Ubuntu trusty *
Libxstream-java Ubuntu upstream *
Libxstream-java Ubuntu xenial *

Extended Description

It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.

Potential Mitigations

  • Make fields transient to protect them from deserialization.
  • An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.

References