--- title: "CVE-2021-21346: XStream is vulnerable to an Arbitrary… | CubePath" 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…" language: en source: https://cubepath.com/security/cve/CVE-2021-21346 --- # CVE-2021-21346: XStream is vulnerable to an Arbitrary… | CubePath ## 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 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. Official description from the CVE record, published by GitHub\_M. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-21346) ## Key data ### CVSS 3.1 Medium 6.1 Score published by GitHub\_M in the CVE record. CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N | Metric | Value | What it means | | ---------------------- | -------- | ----------------------------------------------------------------------------------------- | | Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. | | Attack complexity | High | The attack depends on conditions outside the attacker's control, so it takes preparation. | | Privileges required | None | No account or privileges are needed. | | User interaction | Required | A user has to do something first, such as opening a file or following a link. | | Scope | Changed | The impact can reach other components beyond the vulnerable one. | | Confidentiality impact | None | No effect on the secrecy of data. | | Integrity impact | High | Serious or total effect on the trustworthiness of data. | | Availability impact | None | No effect on availability. | CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) . ### EPSS Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days. Score 0.76367 (76.4% probability) Percentile 99.5% Scores of Nov 10, 2026 Model v2026.06.15 ### CISA assessment as of Oct 7, 2026 Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA. Automatable yes Technical impact total ### Weakness (CWE) CWE catalog version 5.0. CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license. - [CWE-434](https://cwe.mitre.org/data/definitions/434.html) Unrestricted Upload of File with Dangerous Type - [CWE-502](https://cwe.mitre.org/data/definitions/502.html) Deserialization of Untrusted Data ## Affected products Products listed in the CVE record, as the CNA published them. - x-stream xstream - affected: < 1.4.16 ## References Links listed in the CVE record. They lead to other sites, which CubePath does not control. - [x-stream.github.io/security.html](https://x-stream.github.io/security.html#workaround) - [x-stream.github.io/changes.html](http://x-stream.github.io/changes.html#1.4.16) - [github.com/x-stream/xstream/security/advisories/GHSA-4hrm-m…](https://github.com/x-stream/xstream/security/advisories/GHSA-4hrm-m67v-5cxr) - [x-stream.github.io/CVE-2021-21346.html](https://x-stream.github.io/CVE-2021-21346.html) - [\[debian-lts-announce\] 20210403 \[SECURITY\] \[DLA 2616-1\] libxstream-java security update](https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html) (lists.debian.org) mailing-list - [\[jmeter-dev\] 20210406 \[GitHub\] \[jmeter\] sseide opened a new pull request #655: update x-stream to 1.4.16 (from 1.4.15)](https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0%40%3Cdev.jmeter.apache.org%3E) (lists.apache.org) mailing-list - [\[activemq-users\] 20210427 Release date for ActiveMQ v5.16.2 to fix CVEs](https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd%40%3Cusers.activemq.apache.org%3E) (lists.apache.org) mailing-list - [security.netapp.com/advisory/ntap-20210430-0002](https://security.netapp.com/advisory/ntap-20210430-0002/) - [oracle.com//security-alerts/cpujul2021.html](https://www.oracle.com//security-alerts/cpujul2021.html) - [FEDORA-2021-fbad11014a](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/) (lists.fedoraproject.org) vendor-advisory - [FEDORA-2021-d894ca87dc](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/) (lists.fedoraproject.org) vendor-advisory - [oracle.com/security-alerts/cpuoct2021.html](https://www.oracle.com/security-alerts/cpuoct2021.html) - [FEDORA-2021-5e376c0ed9](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/) (lists.fedoraproject.org) vendor-advisory - [DSA-5004](https://www.debian.org/security/2021/dsa-5004) (debian.org) vendor-advisory - [oracle.com/security-alerts/cpujan2022.html](https://www.oracle.com/security-alerts/cpujan2022.html) ## Timeline 1. ID reserved Dec 22, 2020 2. Record published Mar 22, 2021 3. Record last updated Oct 7, 2026 ## Look up another CVE ## About CubePath CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection. [Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection) Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:04 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)