XStream is a simple library to serialize objects to XML and back again. In affected versions this 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. If 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.
Use CWE-502, Xstream vendor hub and Xstream product page to widen CVE-2021-39150 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2021-39152, CVE-2021-39154 and CVE-2021-39153 for nearby disclosures in the same product family.