Oracle Linux: CVE-2021-39151: ELSA-2021-3956: xstream security update (IMPORTANT)

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. 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.
A flaw was found in xstream, a simple library used to serialize objects to XML and back again. This flaw allows a remote attacker to load and execute arbitrary code from a remote host by manipulating the processed input stream. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.