GHSA-4cch-wxpw-8p28
MEDIUMGHSA-4cch-wxpw-8p28 is a medium-severity (CVSS 6.3) Server-Side Request Forgery (SSRF) vulnerability in com.thoughtworks.xstream:xstream. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-4cch-wxpw-8p28 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Server-Side Forgery Request can be activated unmarshalling with XStream
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-4cch-wxpw-8p28 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
Patches
If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.15.
Workarounds
The reported vulnerability does not exist 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 insist to use XStream default blacklist - despite that clear recommendation - can use a workaround depending on their version in use.
Users of XStream 1.4.14 can simply add two lines to XStream's setup code:
xstream.denyTypes(new String[]{ "jdk.nashorn.internal.objects.NativeString" });
xstream.denyTypesByRegExp(new String[]{ ".*\\.ReadAllStream\\$FileStream" });
Users of XStream 1.4.14 to 1.4.13 can simply add three lines to XStream's setup code:
xstream.denyTypes(new String[]{ "javax.imageio.ImageIO$ContainsFilter", "jdk.nashorn.internal.objects.NativeString" });
xstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class });
xstream.denyTypesByRegExp(new String[]{ ".*\\.ReadAllStream\\$FileStream" });
Users of XStream 1.4.12 to 1.4.7 who want to use XStream with a black list will have to setup such a list from scratch and deny at least the following types: javax.imageio.ImageIO$ContainsFilter, java.beans.EventHandler, java.lang.ProcessBuilder, jdk.nashorn.internal.objects.NativeString.class, java.lang.Void and void and deny several types by name pattern.
xstream.denyTypes(new String[]{ "javax.imageio.ImageIO$ContainsFilter", "jdk.nashorn.internal.objects.NativeString" });
xstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class, "jdk.nashorn.internal.objects.NativeString", java.beans.EventHandler.class, java.lang.ProcessBuilder.class, java.lang.Void.class, void.class });
xstream.denyTypesByRegExp(new String[]{ ".*\\$LazyIterator", "javax\\.crypto\\..*", ".*\\.ReadAllStream\\$FileStream" });
Users of XStream 1.4.6 or below can register an own converter to prevent the unmarshalling of the currently know critical types of the Java runtime. It is in fact an updated version of the workaround for CVE-2013-7285:
xstream.registerConverter(new Converter() {
public boolean canConvert(Class type) {
return type != null && (type == java.beans.EventHandler.class || type == java.lang.ProcessBuilder.class
|| type.getName().equals("javax.imageio.ImageIO$ContainsFilter") || type.getName().equals("jdk.nashorn.internal.objects.NativeString")
|| type == java.lang.Void.class || void.class || Proxy.isProxy(type))
|| type.getName().startsWith("javax.crypto.") || type.getName().endsWith("$LazyIterator") || type.getName().endsWith(".ReadAllStream$FileStream"));
}
public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
throw new ConversionException("Unsupported type due to security reasons.");
}
public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
throw new ConversionException("Unsupported type due to security reasons.");
}
}, XStream.PRIORITY_LOW);
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 | 1.4.15 |
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 1.4.15 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4cch-wxpw-8p28 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-4cch-wxpw-8p28 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-4cch-wxpw-8p28. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-4cch-wxpw-8p28 in your dependencies?
O3 detects GHSA-4cch-wxpw-8p28 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.