critical·Product Based Web Vulnerabilities·Updated Feb 10, 2024

CVE-2021-21345 Scanner

Detects 'Remote Code Execution (RCE)' vulnerability in Xstream affects v. before 1.4.16.

Run This Scanner →How to fix it

Est. Time~10 seconds

Scan TypeSingle Scan

Targetsdomain, ipv4, subdomain

CostFree

2.4k

Times Used

continuous scan runs

4.4k

Continuously Checked

assets under CS

Vulnerabilities Found

confirmed findings

References

github.com↗

CVECVE-2021-21345

9.9

CVSSmedium

Exploitable remotely over the internet · low-privilege account sufficient · user interaction needed.

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 who 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. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16.

Attack Vector

Network

Privileges Req.

Low

User Interaction

Required

Affected

xstreamby x-stream

< 1.4.16

Updated Aug 21, 2026View on NVD →

Detail

Affected Software Overview:

Product: XStream
Vulnerable Versions: Versions before 1.4.16
Impact: Attackers with sufficient rights can exploit this vulnerability to execute host commands by manipulating the processed input stream, potentially leading to sensitive information disclosure, data modification, or unauthorized administrative operations.

Vulnerability Details:

CVE-2021-21345 is a severe vulnerability in XStream, allowing remote code execution through deserialization of untrusted input. This flaw exposes applications using XStream for XML processing to significant risks, as attackers can execute arbitrary code on the target system. The vulnerability's critical nature is underscored by its CVSS score of 9.9, highlighting the urgency of addressing this issue.

Severity: Critical
CVSS Score: 9.9
Remediation: Update to XStream version 1.4.16 or later.

The Importance of Addressing CVE-2021-21345:

Mitigating CVE-2021-21345 is vital for maintaining the security and integrity of applications that utilize XStream for XML processing. By addressing this vulnerability, organizations can protect their systems from potential remote code execution attacks, safeguarding sensitive data and preserving operational continuity.

At S4E, we provide targeted solutions like the CVE-2021-21345 Scanner to quickly identify and mitigate vulnerabilities threatening your digital assets. Our platform equips you with the necessary tools and guidance to address critical issues like CVE-2021-21345, enhancing your cybersecurity posture with comprehensive scanning capabilities and expert support. Choose S4E to ensure your applications remain secure against evolving threats in the cybersecurity landscape.

Solution Advice

To protect your systems against CVE-2021-21345, follow these steps:

Update XStream: Ensure that XStream is updated to version 1.4.16 or higher to mitigate the vulnerability.
Validate Input: Implement strict input validation measures to prevent the processing of malicious input.
Monitor for Anomalies: Regularly monitor application logs for unusual activities that might indicate attempts to exploit this vulnerability.

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CVE-2021-21345 Scanner

Vulnerability Details:

The Importance of Addressing CVE-2021-21345:

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