{"id":"CVE-2021-21345","published":"2021-03-22T23:40:25Z","modified":"2026-10-07T18:46:57Z","title":"XStream is vulnerable to a Remote Command Execution attack","vendor":"x-stream","product":"xstream","tier":"core","eol":null,"affectedVersions":[{"vendor":"x-stream","product":"xstream","versions":["< 1.4.16"]}],"description":{"text":"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 who has sufficient rights to execute commands of the 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.","provenance":"source","from":"CVE.org"},"summary":{"text":"XStream, a Java library for serializing objects to XML and back, contains a flaw in versions before 1.4.16 that allows deserialization-driven remote command execution on the host. An attacker with sufficient rights who can supply a crafted input stream over the network can trigger this, though it requires user interaction, a high-complexity condition, and does not affect deployments that use an explicit whitelist of minimal required types.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T07:13:35Z"},"cvss":{"score":5.8,"severity":"MEDIUM","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:N","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.72324,"percentile":0.99435,"date":"2026-10-29","provenance":"source"},"kev":null,"vulncheckKev":null,"exploited":false,"otx":{"pulseCount":0,"pulses":[],"provenance":"machine"},"cwes":[{"id":"CWE-94","name":"Improper Control of Generation of Code"},{"id":"CWE-502","name":"Deserialization of Untrusted Data"}],"references":[{"url":"https://x-stream.github.io/security.html#workaround","tags":["x_refsource_MISC"]},{"url":"http://x-stream.github.io/changes.html#1.4.16","tags":["x_refsource_MISC"]},{"url":"https://github.com/x-stream/xstream/security/advisories/GHSA-hwpc-8xqv-jvj4","tags":["x_refsource_CONFIRM"]},{"url":"https://x-stream.github.io/CVE-2021-21345.html","tags":["x_refsource_MISC"]},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0%40%3Cdev.jmeter.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd%40%3Cusers.activemq.apache.org%3E","tags":["mailing-list","x_refsource_MLIST"]},{"url":"https://www.oracle.com/security-alerts/cpuApr2021.html","tags":["x_refsource_MISC"]},{"url":"https://security.netapp.com/advisory/ntap-20210430-0002/","tags":["x_refsource_CONFIRM"]},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","tags":["x_refsource_MISC"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/","tags":["vendor-advisory","x_refsource_FEDORA"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/","tags":["vendor-advisory","x_refsource_FEDORA"]},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","tags":["x_refsource_MISC"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/","tags":["vendor-advisory","x_refsource_FEDORA"]},{"url":"https://www.debian.org/security/2021/dsa-5004","tags":["vendor-advisory","x_refsource_DEBIAN"]},{"url":"https://www.oracle.com/security-alerts/cpujan2022.html","tags":["x_refsource_MISC"]}],"techniques":[],"reports":[],"affected":[{"ecosystem":"Maven","package":"com.thoughtworks.xstream:xstream","vulnerableRanges":["<1.4.16"],"patched":["1.4.16"],"from":["GHSA-hwpc-8xqv-jvj4"],"provenance":"source"}],"advisories":[{"id":"GHSA-hwpc-8xqv-jvj4","url":"https://github.com/advisories/GHSA-hwpc-8xqv-jvj4","severity":"MODERATE","ecosystem":"Maven","package":"com.thoughtworks.xstream:xstream","vulnerableRanges":["<1.4.16"],"patched":["1.4.16"],"provenance":"source","from":"GHSA"}],"euvd":{"id":"EUVD-2021-0674","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-0674","exploited":false,"exploitedSince":null,"provenance":"source"},"exploits":[],"exploitSources":{"nuclei":[{"id":"CVE-2021-21345","name":"XStream < 1.4.16 - Remote Code Execution","severity":"critical","path":"http/cves/2021/CVE-2021-21345.yaml","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21345.yaml"}],"provenance":"source"},"exploitRefs":[],"flow":[],"timeline":[{"date":"2021-03-22","kind":"published","label":"Published (CVE.org)","url":"https://www.cve.org/CVERecord?id=CVE-2021-21345","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":null},"priority":{"score":28.9,"factors":[{"name":"In a KEV catalog","points":0.0,"detail":"not listed"},{"name":"Recent KEV listing","points":0.0,"detail":"not listed"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":19.89,"detail":"percentile 0.9943"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"1 nuclei template"},{"name":"Mentioned in OTX pulses","points":0.0,"detail":"0 pulses"},{"name":"CVSS severity","points":4.06,"detail":"base score 5.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}