### ImpactThe vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream with a Java runtime version 14 to 8. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.### PatchesIf you rely on XStream's default blacklist of the [Security Framework](https://x-stream.github.io/security.html#framework), you will have to use at least version 1.4.18.### WorkaroundsSee [workarounds](https://x-stream.github.io/security.html#workaround) for the different versions covering all CVEs.### ReferencesSee full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for [CVE-2021-39150](https://x-stream.github.io/CVE-2021-39150.html).### CreditsLai Han of NSFOCUS security team found and reported the issue to XStream and provided the required information to reproduce it.### For more informationIf you have any questions or comments about this advisory:* Open an issue in [XStream](https://github.com/x-stream/xstream/issues)* Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)