CVE intelligence and bounded remediation

CVE-2021-21341 — XStream is a Java library to serialize objects to XML and back again

High CVSS 7.5

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.

Severity
High
CVSS
7.5 (3.1)
Published
2021-03-23
CISA KEV
Not currently listed
Ecosystem
java/maven
Weaknesses
CWE-400, CWE-502

Affected products

  • netapp / oncommand_insight
  • apache / activemq
  • apache / activemq / 5.16.0
  • apache / activemq / 5.16.1
  • apache / jmeter
  • xstream / xstream

Showing 6 representative product identities from 34 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Unsafe deserialization and object reconstruction

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Check exposure

  • Inventory serialization formats accepted from requests, queues, caches, files, cookies, and cross-service messages.
  • Trace whether untrusted input can select classes, types, callbacks, constructors, or object hooks during decoding.
  • Identify signing, schema validation, trust-boundary, and compatibility settings for each decoder.

Remediate safely

  • Replace native object deserialization with a data-only format and explicit schema validation.
  • If replacement is not immediate, use a safe decoder with a minimal type allowlist and disable polymorphic or executable hooks.
  • Update the affected library and add inert tests for unknown types, extra fields, malformed nesting, and unsigned data.

Authoritative sources

Complete CVE record and remediation plan

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