Xstream
CVE-2021-21342
CRITICAL
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A08:2025 - Software or Data Integrity Failures
ASVS 5.0
V1 - Encoding and Sanitization Safe deserialization, type allowlists
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 9.1 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could execute arbitrary code through malicious serialized objects by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Avoid deserializing untrusted data. Use safe serialization formats (JSON). Implement integrity checks and type allowlists.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in maven
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Deserialization of Untrusted Data (CWE-502), which allows attackers to execute arbitrary code through malicious serialized objects. XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability where 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. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16. Affected products include: Netapp Oncommand Insight, Apache Activemq, Apache Jmeter, Xstream, Debian Debian Linux. Version information: version 1.4.16.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability where 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. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.
Affected Products (CPE)NVD
XStream before version 1.4.14 is vulnerable to Remote Code Execution.The vulnerability may allow a remote attacker to ru
XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.1), this vulnerabi
XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.8), this vulnerabi
XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.8), this vulnerabi
XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.9), this vulnerabi
XStream is software for serializing Java objects to XML and back again. Rated high severity (CVSS 8.8), this vulnerabili
XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 7.7), this vulnerability
XStream is a Java library to serialize objects to XML and back again. Rated medium severity (CVSS 6.8), this vulnerabili
XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 7.5), this vulnerability
XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 8.6), this vulnerability
XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 7.5), this vulnerability
XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.8), this vulnerabi
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