# CVE-2021-39144: XStream is vulnerable to a Remote Command Execution attack

Source: https://junglewise.ai/threats/cve-2021-39144-xstream-remote-code-execution-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-08-25. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-39144 · Severity: critical · CVSS 3.1 · Exploited in the wild · Published 2021-08-25

XStream is vulnerable to Remote Code Execution (RCE) via unsafe deserialization of untrusted data. An attacker can manipulate the processed XML input stream to inject objects that execute arbitrary local commands on the server, particularly when XStream's security framework is not configured with a strict whitelist.

Technologies: [com.thoughtworks.xstream:xstream (Maven)](https://junglewise.ai/threats/technologies/com-thoughtworks-xstream-xstream). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2021-39144 exploited in the wild?** Yes. CVE-2021-39144 is known to be exploited in the wild, first recorded on 10 March 2023. Treat it as urgent.

**How severe is CVE-2021-39144?** Critical severity, with a CVSS score of 3.1, published 25 August 2021.

**Which products and versions are affected?** com.thoughtworks.xstream:xstream (Maven) ECOSYSTEM:introduced=0,fixed=1.4.18.

**Is there a fix for CVE-2021-39144?** Yes. com.thoughtworks.xstream:xstream (Maven): upgrade to 1.4.18 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2021-39144 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2021-39144?** Check whether you run com.thoughtworks.xstream:xstream (Maven) or XStream at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- com.thoughtworks.xstream:xstream (Maven): upgrade to 1.4.18 or later

  ```sh
  # set com.thoughtworks.xstream:xstream to 1.4.18 in your pom.xml or build.gradle
  ```


## Affected products

- XStream Project XStream versions prior to 1.4.18
- VMware Cloud Foundation
- VMware NSX Manager

## Identifiers

- CVE-2021-39144
- GHSA-j9h8-phrw-h4fh

## Timeline

- 2021-08-22: disclosed: Initial vulnerability disclosure and XStream 1.4.18 release
- 2023-03-10: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2023-03-10: exploited: Confirmed active exploitation in the wild

## Related threats

- [XStream is vulnerable to a Denial of Service attack due to stack overflow from a manipulated binary input stream](https://junglewise.ai/threats/cve-2024-47072-xstream-is-vulnerable-to-a-denial-of-service-attack-due-to-stack)
- [XStream can cause a Denial of Service by injecting deeply nested objects raising a stack overflow](https://junglewise.ai/threats/cve-2022-40151-xstream-can-cause-a-denial-of-service-by-injecting-deeply-nested)
- [XStream can cause Denial of Service via stack overflow](https://junglewise.ai/threats/cve-2022-41966-xstream-can-cause-denial-of-service-via-stack-overflow)
- [Duplicate Advisory: Denial of Service due to parser crash](https://junglewise.ai/threats/duplicate-advisory-denial-of-service-due-to-parser-crash-92e16523)
- [Denial of Service by injecting highly recursive collections or maps in XStream](https://junglewise.ai/threats/cve-2021-43859-denial-of-service-by-injecting-highly-recursive-collections-or)