ELA-488-1 libxstream-java security update

remote code execution

Related CVEs CVE-2021-39139 CVE-2021-39140 CVE-2021-39141 CVE-2021-39144 CVE-2021-39145 CVE-2021-39146 CVE-2021-39147 CVE-2021-39148 CVE-2021-39149 CVE-2021-39150 CVE-2021-39151 CVE-2021-39152 CVE-2021-39153 CVE-2021-39154

Multiple security vulnerabilities have been discovered in XStream, a Java library to serialize objects to XML and back again.

These vulnerabilities may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream.

XStream itself sets up a whitelist by default now, i.e. it blocks all classes except those types it has explicit converters for. It used to have a blacklist by default, i.e. it tried to block all currently known critical classes of the Java runtime. Main reason for the blacklist were compatibility, it allowed to use newer versions of XStream as drop-in replacement. However, this approach has failed. A growing list of security reports has proven, that a blacklist is inherently unsafe, apart from the fact that types of 3rd libraries were not even considered. A blacklist scenario should be avoided in general, because it provides a false sense of security.

See also https://x-stream.github.io/security.html#framework

For Debian 8 jessie, these problems have been fixed in version

We recommend that you upgrade your libxstream-java packages.

Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/