# CVE-2020-26258: libxstream-java: XStream is a Java library to serialize objects to XML and back again

CVE-2020-26258 is fixed in libxstream-java on 1 platform, first by libxstream-java 1.4.11.1-1~18.04.1, released December 15, 2020. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2020-26258
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.8182
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 15, 2020

## Description

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.15, a Server-Side Forgery Request vulnerability can be activated when unmarshalling. The vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.15. The reported vulnerability does not exist if running Java 15 or higher. No user is affected who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability. Users of XStream 1.4.14 or below who still want to use XStream default blacklist can use a workaround described in more detailed in the referenced advisories.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxstream-java Ubuntu 18.04.6 LTS (bionic) | 1.4.11.1-1~18.04.1 | [libxstream-java 1.4.11.1-1~18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libxstream-java-1.4.11.1-1-18.04.1.md) | Dec 15, 2020 |
| Linux | libxstream-java Ubuntu 20.04 LTS (focal) | 1.4.11.1-1ubuntu0.1 | [libxstream-java 1.4.11.1-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libxstream-java-1.4.11.1-1ubuntu0.1.md) | Dec 15, 2020 |

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