Xstream
CVE-2021-21347
CRITICAL
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK
2 techniques across 2 tactics: Command and Control, Persistence The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 9.8 (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 upload malicious files that can be executed on the server 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 9.8), 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. Validate file types server-side, store uploads outside webroot, use random filenames, scan for malware.
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 Unrestricted File Upload (CWE-434), which allows attackers to upload malicious files that can be executed on the server. XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability which 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. 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:H
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 which 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. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16.
Blast Radius
ecosystem impact- 1,342 maven packages depend on com.thoughtworks.xstream:xstream (145 direct, 1,199 indirect)
Ecosystem-wide dependent count for version 1.4.16.
Threat Intelligence Overview
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
Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.
Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.
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 critical severity (CVSS 9.1), this vulnerabi
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
NVD
CVE.org
EPSS
GitHub
Exploit-DB