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 hostGHSA-hvv8-336g-rx3m
MEDIUMGHSA-hvv8-336g-rx3m is a medium-severity (CVSS 5.3) Deserialization of Untrusted Data vulnerability in com.thoughtworks.xstream:xstream. 1 public exploit reference exists, so weaponization risk is real. A fix is available for com.thoughtworks.xstream:xstream — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hvv8-336g-rx3m.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-hvv8-336g-rx3m by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 386,684 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
com.thoughtworks.xstream:xstreamReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The processed stream at unmarshalling time contains type information to recreate the formerly written objects. XStream creates therefore new instances based on these type information. An attacker can manipulate the processed input stream and replace or inject objects, that result in a server-side forgery request. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.
Patches
If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16
Workarounds
See workarounds for the different versions covering all CVEs.
References
See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for CVE-2021-21342.
Credits
钟潦贵 (Liaogui Zhong) found and reported the issue to XStream and provided the required information to reproduce it.
For more information
If you have any questions or comments about this advisory:
- Open an issue in XStream
- Contact us at XStream Google Group
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.thoughtworks.xstream:xstream | all versions | 1.4.16com.thoughtworks.xstream:xstream:1.4.16 |
Affected Products
activemqapachejmeterapachedebian linuxdebianfedorafedoraprojectoncommand insightnetappbanking enterprise default managementoracleResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.thoughtworks.xstream:xstream, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.thoughtworks.xstream:xstream to 1.4.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hvv8-336g-rx3m is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
OpenShift Container Platform (OCP) delivers Jenkins LTS package with bundled XStream library. Due to JEP-200 [1] and JEP-228 [2] Jenkins projects, OCP Jenkins package is not affected by this flaw. [1] https://github.com/jenkinsci/jep/blob/master/jep/200/README.adoc [2]…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Data Grid 8.2.0 | xstream | RHSA-2021:2139 |
| Red Hat Fuse 7.10 | xstream | RHSA-2021:5134 |
| Red Hat Integration | see advisory | RHSA-2021:4918 |
| Red Hat Integration Camel Quarkus 2 | see advisory | RHSA-2021:4767 |
| RHDM 7.11.0 | xstream | RHSA-2021:2476 |
| RHPAM 7.11.0 | xstream | RHSA-2021:2475 |
Frequently Asked Questions
Is GHSA-hvv8-336g-rx3m in your dependencies?
Find it across Maven, including transitive dependencies.