# CVE-2021-21343: libxstream-java: XStream is a Java library to serialize objects to XML and back again

CVE-2021-21343 is fixed in libxstream-java on 1 platform, first by libxstream-java 1.4.11.1-1~18.04.2, released March 22, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-21343
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.4667
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 22, 2021

## Description

XStream is a Java library to serialize objects to XML and back again. InXStream before version 1.4.16, there is a vulnerability where the processedstream at unmarshalling time contains type information to recreate theformerly written objects. XStream creates therefore new instances based onthese type information. An attacker can manipulate the processed inputstream and replace or inject objects, that result in the deletion of a fileon the local host. No user is affected, who followed the recommendation tosetup XStream's security framework with a whitelist limited to the minimalrequired types. If you rely on XStream's default blacklist of the SecurityFramework, you will have to use at least version 1.4.16.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxstream-java Ubuntu 18.04.6 LTS (bionic) | 1.4.11.1-1~18.04.2 | [libxstream-java 1.4.11.1-1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libxstream-java-1.4.11.1-1-18.04.2.md) | Mar 22, 2021 |
| Linux | libxstream-java Ubuntu 20.04 LTS (focal) | 1.4.11.1-1ubuntu0.2 | [libxstream-java 1.4.11.1-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libxstream-java-1.4.11.1-1ubuntu0.2.md) | Mar 22, 2021 |
| Linux | libxstream-java Ubuntu 24.10 (oracular) | 1.4.15-2 | [libxstream-java 1.4.15-2](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libxstream-java-1.4.15-2.md) | Jan 16, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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