CVE-2021-39144

CVE-2021-39144 is a remote code execution vulnerability in XStream, a widely used Java library that serializes objects to XML and back, caused by unsafe deserialization of a manipulated input stream (CWE-502, CWE-94, CWE-306). An attacker with sufficient rights to feed crafted input into an application running an affected XStream version can trigger arbitrary type instantiation and execute commands on the host, with high impact to confidentiality, integrity and availability (CVSS 3.1: 8.5, scope changed). Only deployments relying on XStream's default blacklist configuration are affected; users who configured XStream's security framework with a whitelist limited to the minimal required types are not affected, and XStream 1.4.18 removed the vulnerable default blacklist behavior. The library is embedded in many downstream products in the data, including Debian Linux and Fedora packages, NetApp SnapManager, and numerous Oracle Communications, Commerce and Retail products, and it was exploited in VMware Cloud Foundation and NSX Manager. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2023-03-10, is being actively exploited in the wild per current headlines, and EPSS assigns a 98.1% probability of exploitation within 30 days.

What to do: Upgrade XStream to 1.4.18 or later, or configure its security framework with a whitelist limited to the minimal required types; apply vendor-supplied updates for VMware Cloud Foundation/NSX Manager, Oracle, NetApp, Debian and Fedora per the CISA KEV required action. Prioritize internet-exposed VMware NSX Manager and Cloud Foundation deployments, which are being actively exploited, and audit any applications that pass untrusted XML input into XStream.