XStream is vulnerable to an Arbitrary Code Execution attackGHSA-p8pq-r894-fm8f
HIGHGHSA-p8pq-r894-fm8f is a high-severity (CVSS 8.5) Unrestricted File Upload vulnerability in com.thoughtworks.xstream:xstream. EPSS puts its 30-day exploitation probability at 14.3% (97th percentile). 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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-p8pq-r894-fm8f.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-p8pq-r894-fm8f by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 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 vulnerability 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.
Patches
XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
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-2021-39146.
Credits
Ceclin and YXXX from the Tencent Security Response Center 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 | 1.4.18com.thoughtworks.xstream:xstream:1.4.18 |
Affected Products
debian linuxdebianfedorafedoraprojectsnapmanagernetappbusiness activity monitoringoraclecommerce guided searchoraclecommunications billing and revenue management elastic charging engineoracleDetection & 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 1.4.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-p8pq-r894-fm8f is resolved across your whole dependency graph.
Workarounds
Treat uploaded files as untrusted until proven otherwise: validate the actual content type rather than the supplied extension, store uploads outside the web root on a volume mounted without execute permission, and rename them to server-generated identifiers so an attacker cannot choose the path a request will later resolve.
How to detect GHSA-p8pq-r894-fm8f
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id ghsa-p8pq-r894-fm8f -u https://target- Template
- XStream 1.4.18 - Arbitrary Code Execution
- Severity
- high
- Impact
- Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected system.
- Remediation
- Upgrade XStream to a version that is not affected by CVE-2021-39146.
Template by ProjectDiscovery nuclei-templates (pwnhxl), MIT licensed. View the full template. Scan only systems you are authorised to test.
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. XStream 1.4.18 no longer uses a blacklist by default since it cannot be secured for general purposes. OpenShift Container Platform (OCP) delivers the Jenkins LTS package with bundled…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Data Grid 8.3.0 | xstream | RHSA-2022:0520 |
| Red Hat Enterprise Linux 7 | xstream-0:1.3.1-16.el7_9 | RHSA-2021:3956 |
| Red Hat Integration | see advisory | RHSA-2021:4918 |
| Red Hat Integration Camel Quarkus 2 | see advisory | RHSA-2021:4767 |
| RHDM 7.12.0 | xstream | RHSA-2022:0297 |
| RHPAM 7.12.0 | xstream | RHSA-2022:0296 |
Frequently Asked Questions
Is GHSA-p8pq-r894-fm8f in your dependencies?
Find it across Maven, including transitive dependencies.