GHSA-xw4p-crpj-vjx2
HIGHGHSA-xw4p-crpj-vjx2 is a high-severity (CVSS 8.5) Deserialization of Untrusted Data vulnerability in com.thoughtworks.xstream:xstream. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-xw4p-crpj-vjx2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
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 host
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 vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream with a Java runtime version 14 to 8. 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 1.4.18.
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-2021-39152.
Credits
m0d9 of the Security Team of Alibaba Cloud 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 | 1.4.18 |
Research 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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update com.thoughtworks.xstream:xstream to 1.4.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xw4p-crpj-vjx2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-xw4p-crpj-vjx2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-xw4p-crpj-vjx2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
Users who follow the recommended security framework with a whitelist to limit the types to the minimum required should not be affected. If you rely on XStream's default blacklist of the [Security Framework](https://x-stream.github.io/security.html#framework), you will have to use at least version 1.4.18. OpenShift…
Frequently Asked Questions
Is GHSA-xw4p-crpj-vjx2 in your dependencies?
O3 detects GHSA-xw4p-crpj-vjx2 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.