CVE-2021-39144
XStream Remote Code Execution Vulnerability
IN CISA KEV
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.
- Vendor
- XStream
- Product
- XStream
- CVSS 3.1
- 8.5 (high), scored by NVD (primary)CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- CVSS 3.1
- 8.5 (high), scored by security-advisories@github.comCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- Published
- 2021-08-23
- NVD modified
- 2026-06-17
- NVD status
- Analyzed
CISA KEV
- Date added
- 2023-03-10
- Due date
- 2023-03-31
- Ransomware use
- Unknown
- Required action
- Apply updates per vendor instructions.
EPSS
98.1% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- github.com (Vendor Advisory)
- lists.debian.org (Mailing List, Third Party Advisory)
- lists.fedoraproject.org (Broken Link, Mailing List, Release Notes)
- lists.fedoraproject.org (Broken Link, Mailing List, Release Notes)
- lists.fedoraproject.org (Broken Link, Mailing List, Release Notes)
- security.netapp.com (Third Party Advisory)
- www.debian.org (Third Party Advisory)
- www.oracle.com (Patch, Third Party Advisory)
- www.oracle.com (Patch, Third Party Advisory)
- www.oracle.com (Patch, Third Party Advisory)
- github.com (Vendor Advisory)
- lists.debian.org (Mailing List, Third Party Advisory)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.