CVE-2021-39139

What it is

XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream. A user is only affected if using the version out of the box with JDK 1.7u21 or below. However, this scenario can be adjusted easily to an external Xalan that works regardless of the version of the Java runtime. 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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

4.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-08-23 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-07 21:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 4.5% in the next 30 days (EPSS).
• Severity: 8.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-08-23 18:15 UTC

Last modified

2026-10-07 21:17 UTC

Exploit probability

4.5% · EPSS, next 30 days

Weakness

CWE-434 · Unrestricted file upload

Record status

Analyzed

Affected

• Xstream < 1.4.18
• Debian Linux 9.0
• Debian Linux 10.0
• Debian Linux 11.0
• Fedoraproject Fedora 33
• Fedoraproject Fedora 34
• Fedoraproject Fedora 35
• Netapp Snapmanager

Attack profile CVSS 3.1 · 8.5

Attack vector

Network

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-39139.md and follow it. Check whether this project is affected by CVE-2021-39139. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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