Reference page — cumulative record through Thursday, October 8, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-39147

CVE-2021-39147HIGH

x-stream xstream — XStream is vulnerable to an Arbitrary Code Execution attack

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   H   L   N  C  H  H  H    8.5   .0474   91.6     —

AFFECTED
  Product  Versions    Fixed
  xstream  < 1.4.18 –  —

TIMELINE
  Aug 16  Reserved by GitHub_M
  Aug 23  Published (CNA: GitHub_M)
  Oct 7   EXPLOIT PUBLISHED — CVE-2021-39147 (x-stream xstream). Public exploit reference added.

CWE-434, CWE-502 · CNA: GitHub_M · CVSS v3.1 · 11 references · NVD status: Analyzed

Description

XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker to load and execute arbitrary code from a remote 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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
August 16, 2021	Reserved	Reserved by GitHub_M
August 23, 2021	Published	Published (CNA: GitHub_M)
October 7, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-39147 (x-stream xstream). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
x-stream	xstream	—	< 1.4.18	—

Weaknesses

CWE-434 · CWE-502

References (11)

https://github.com/x-stream/xstream/security/advisories/GHSA-h7v4-7xg3-hxcc [Third Party Advisory]
https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html [Mailing List, Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/ [Mailing List]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/ [Mailing List]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/ [Mailing List]
https://security.netapp.com/advisory/ntap-20210923-0003/ [Third Party Advisory]
https://www.debian.org/security/2021/dsa-5004 [Third Party Advisory]
https://www.oracle.com/security-alerts/cpuapr2022.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpujan2022.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpujul2022.html [Third Party Advisory]
https://x-stream.github.io/CVE-2021-39147.html [Exploit, Third Party Advisory]

Authoritative record: CVE-2021-39147 at cve.org

Vendors: x-stream

Weaknesses: CWE-434 · CWE-502

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-39147 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Thursday, October 8, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.