CVE-2021-21344
MEDIUMEPSS 99th pctlDescription
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 to load and execute arbitrary code from a remote 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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
References
Related Vulnerabilities
Other CWE-434 (Unrestricted File Upload) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-12617 | High | 8.1 | 100% | KEV | Fix |
| CVE-2018-15961 | Critical | 9.8 | 100% | KEV | - |
| CVE-2021-31207 | Medium | 6.6 | 100% | KEV + Ransom | Fix |
| CVE-2017-12615 | High | 8.1 | 100% | KEV + Ransom | - |
| CVE-2025-31324 | Critical | 10.0 | 99% | KEV + Ransom | - |
| CVE-2024-50623 | Critical | 9.8 | 99% | KEV + Ransom | Fix |
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Markdown
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TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.
This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-05-23.