CVE-2021-21351
XStream is vulnerable to an Arbitrary Code Execution attack
- Published
- Mar 22, 2021
- Updated
- Oct 7, 2026
- Assigning CNA
- GitHub_M
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:HHigh · next 30 days
- Percentile
- 99.7%
- Model date
- Oct 17, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability 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.
Sources
xstream/CVE-2021-21351
XStream Deserialization Remote Command Execution (CVE-2021-21351)
Vulhub vulnerability labsDeclared conditions
- lab image version: vulhub/xstream:1.4.15(xstream/CVE-2021-21351/docker-compose.yml:services.web.image)
http/cves/2021/CVE-2021-21351.yaml
Nuclei TemplatesDeclared conditions
- network: http($.protocol_keys)
- verification: status,word($.matchers[*].type)
- oob: interactsh_reference($.template_text)
Responsible use
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