XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream, if using the version out of the box with Java runtime version 14 to 8 or with JavaFX installed. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.

XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.