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-2021-21349

CVE-2021-21349HIGH

x-stream xstream — A Server-Side Forgery Request can be activated unmarshalling with XStream to access data streams from an arbitrary URL referencing a resource in an intranet or the local host

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  C  H  N  N    8.6   .4683   98.8     —

AFFECTED
  Product  Versions    Fixed
  xstream  < 1.4.16 –  —

TIMELINE
  Dec 22  Reserved by GitHub_M
  Mar 22  Published (CNA: GitHub_M)
  Oct 7   EXPLOIT PUBLISHED — CVE-2021-21349 (x-stream xstream). Public exploit reference added.
  Oct 7   RESCORED — CVE-2021-21349 (x-stream xstream). CVSS 6.1 → 8.6 (NVD).

CWE-918, CWE-502 · CNA: GitHub_M · CVSS v3.1 · 15 references · NVD status: Analyzed

Description

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability which may allow a remote attacker to request data from internal resources that are not publicly available 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. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
December 22, 2020	Reserved	Reserved by GitHub_M
March 22, 2021	Published	Published (CNA: GitHub_M)
October 7, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-21349 (x-stream xstream). Public exploit reference added.
October 7, 2026	RESCORED	RESCORED — CVE-2021-21349 (x-stream xstream). CVSS 6.1 → 8.6 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
x-stream	xstream	—	< 1.4.16	—

Weaknesses

CWE-918 · CWE-502

References (15)

http://x-stream.github.io/changes.html#1.4.16 [Release Notes, Third Party Advisory]
https://github.com/x-stream/xstream/security/advisories/GHSA-f6hm-88x3-mfjv [Third Party Advisory]
https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd%40%3Cusers.activemq.apache.org%3E [Issue Tracking, Mailing List, Third Party Advisory]
https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0%40%3Cdev.jmeter.apache.org%3E [Issue Tracking, Mailing List, Third Party Advisory]
https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html [Mailing List, Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/ [Mailing List, Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/ [Mailing List, Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/ [Mailing List, Third Party Advisory]
https://security.netapp.com/advisory/ntap-20210430-0002/ [Third Party Advisory]
https://www.debian.org/security/2021/dsa-5004 [Mailing List, Third Party Advisory]
https://www.oracle.com//security-alerts/cpujul2021.html [Third Party Advisory]
https://www.oracle.com/security-alerts/cpujan2022.html [Patch, Vendor Advisory]
https://www.oracle.com/security-alerts/cpuoct2021.html [Third Party Advisory]
https://x-stream.github.io/CVE-2021-21349.html [Exploit, Third Party Advisory]
https://x-stream.github.io/security.html#workaround [Mitigation, Third Party Advisory]

Authoritative record: CVE-2021-21349 at cve.org

Vendors: x-stream

Weaknesses: CWE-918 · CWE-502

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-21349 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.