The 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.
If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16.
See workarounds for the different versions covering all CVEs.
See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for CVE-2021-21346.
wh1t3p1g G5-RD6@IIE found and reported the issue to XStream and provided the required information to reproduce it.
If you have any questions or comments about this advisory: * Open an issue in XStream * Contact us at XStream Google Group