CVE-2021-29505
HIGHEPSS 100th pctlDescription
XStream is software for serializing Java objects to XML and back again. A vulnerability in XStream versions prior to 1.4.17 may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types is affected. The vulnerability is patched in version 1.4.17.
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:L/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
References
Related Vulnerabilities
Other CWE-94 (Code Injection) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-9841 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2015-1635 | Critical | 9.8 | 100% | KEV | - |
| CVE-2025-3248 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2022-22954 | Critical | 9.8 | 100% | KEV + Ransom | - |
| CVE-2021-22204 | Medium | 6.8 | 100% | KEV | Fix |
| CVE-2012-0158 | High | 8.8 | 100% | KEV | - |
Common questions
How do I fix CVE-2021-29505?
Upgrade libxstream-java on debian 11 to 1.4.15-3 or later.
Is CVE-2021-29505 being actively exploited?
Not that we know of. CVE-2021-29505 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 77.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 100% of all scored CVEs.
How severe is CVE-2021-29505?
CVE-2021-29505 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-29505 affect?
Published advisories record a fix for libxstream-java (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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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 2025-05-30.