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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Code injection prevention, sandbox exec
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 8.5 (HIGH). Attack characteristics: network attack vector, high complexity, low privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

A remote attacker could inject and execute arbitrary code within the application by sending crafted requests to the affected application.

Act Now Prioritize within 24-48h. Why: In CISA KEV with patch available.
Exploited in the wild (CISA KEV) Patch available 98.1% exploitation probability (EPSS)

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AnalysisAI

XStream is a simple library to serialize objects to XML and back again. Rated high severity (CVSS 8.5), this vulnerability is remotely exploitable. Public exploit code available.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Never evaluate user-controlled input as code. Use sandboxing, disable dangerous functions, apply strict input validation.

Affected Packages

maven com.thoughtworks.xstream:xstream fix: 1.4.18

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 Code Injection (CWE-94), which allows attackers to inject and execute arbitrary code within the application. XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the 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. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose. Affected products include: Xstream, Debian Debian Linux, Fedoraproject Fedora, Netapp Snapmanager, Oracle Business Activity Monitoring.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.5 HIGH
AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Added to CISA KEV
Jul 14, 2026 - 04:22 CISA
CVE Published
Aug 23, 2021 - 18:15 nvd
HIGH 8.5

DescriptionNVD

XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the 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. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 1,777 maven packages depend on com.thoughtworks.xstream:xstream (204 direct, 1,576 indirect)

Ecosystem-wide dependent count for version 1.4.18.

Threat Intelligence Overview

EPSS Score
98.1%
Top 0% exploitable
Exploit
POC
Public exploit code exists
Data Quality
4 sources
Confidence: Medium

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.

SignalValue
Severity HIGH
CISA KEV Yes
Public POC Yes
EPSS 98.1%
Patch available Yes
Active threat Yes
Deciding rule
In CISA KEV with patch available
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Out-of-Cycle
Exploitation· derived
Active
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
High

Priority Score

225
Low Medium High Critical
KEV: +50
EPSS: +98
CVSS: +42
PoC: +20
Weaponized: +15
Threat intel: 0
Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

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

cpe:2.3:a:xstream:xstream:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
cpe:2.3:a:netapp:snapmanager:-:*:*:*:*:oracle:*:*
cpe:2.3:a:netapp:snapmanager:-:*:*:*:*:sap:*:*
cpe:2.3:a:oracle:business_activity_monitoring:12.2.1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:commerce_guided_search:11.3.2:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_billing_and_revenue_management_elastic_charging_engine:11.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_billing_and_revenue_management_elastic_charging_engine:12.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_automated_test_suite:1.9.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:1.10.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_unified_inventory_management:7.3.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_unified_inventory_management:7.3.5:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_unified_inventory_management:7.4.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_unified_inventory_management:7.4.1:*:*:*:*:*:*:*
+ 16 more
CVE-2020-26217 HIGH POC
8.8 Nov 16

XStream before version 1.4.14 is vulnerable to Remote Code Execution.The vulnerability may allow a remote attacker to ru

CVE-2021-21351 CRITICAL POC
9.1 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.1), this vulnerabi

CVE-2021-21346 CRITICAL POC
9.8 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.8), this vulnerabi

CVE-2021-21344 CRITICAL POC
9.8 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.8), this vulnerabi

CVE-2021-21345 CRITICAL POC
9.9 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.9), this vulnerabi

CVE-2021-29505 HIGH POC
8.8 May 28

XStream is software for serializing Java objects to XML and back again. Rated high severity (CVSS 8.8), this vulnerabili

CVE-2020-26258 HIGH POC
7.7 Dec 16

XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 7.7), this vulnerability

CVE-2020-26259 MEDIUM POC
6.8 Dec 16

XStream is a Java library to serialize objects to XML and back again. Rated medium severity (CVSS 6.8), this vulnerabili

CVE-2021-21341 HIGH POC
7.5 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 7.5), this vulnerability

CVE-2021-21342 CRITICAL POC
9.1 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated critical severity (CVSS 9.1), this vulnerabi

CVE-2021-21349 HIGH POC
8.6 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 8.6), this vulnerability

CVE-2021-21343 HIGH POC
7.5 Mar 23

XStream is a Java library to serialize objects to XML and back again. Rated high severity (CVSS 7.5), this vulnerability

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