XStream Remote Code Execution Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
Required action
Apply updates per vendor instructions.
CISA notes
https://www.vmware.com/security/advisories/VMSA-2022-0027.html, https://x-stream.github.io/CVE-2021-39144.html; https://nvd.nist.gov/vuln/detail/CVE-2021-39144
Description
XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the 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. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
Severity
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:HExploitation Context
as of October 14, 2026- CISA added CVE-2021-39144 to the KEV catalog 564 days after its CVE record was published. The median for entries added in 2023 is 12 days.
- Its current EPSS score (98.1%) is higher than that of 84% of CISA KEV entries.
Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| x-stream | x-stream xstream | < 1.4.18 |
References
12 Links- https://github.com/x-stream/xstream/security/advisories/GHSA-j9h8-phrw-h4fh
- https://x-stream.github.io/CVE-2021-39144.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://security.netapp.com/advisory/ntap-20210923-0003/
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- http://packetstormsecurity.com/files/169859/VMware-NSX-Manager-XStream-Unauthenticated-Remote-Code-Execution.html
Record Details
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Tool categories
CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.