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-2021-21351
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 L H N C H H H 9.1 .8214 99.6 —
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-2021-21351 (x-stream xstream). Public exploit reference added.
Oct 7 RESCORED — CVE-2021-21351 (x-stream xstream). CVSS 5.4 → 9.1 (NVD).
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 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. 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-2021-21351 (x-stream xstream). Public exploit reference added. |
| October 7, 2026 | RESCORED | RESCORED — CVE-2021-21351 (x-stream xstream). CVSS 5.4 → 9.1 (NVD). |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| x-stream | xstream | — | < 1.4.16 | — |
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-hrcp-8f3q-4w2c [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-2021-21351.html [Exploit, Third Party Advisory]
- https://x-stream.github.io/security.html#workaround [Mitigation, Third Party Advisory]
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-21351 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.
