{"id":"CVE-2021-21341","published":"2021-03-22T23:40:44Z","modified":"2026-10-07T18:42:03Z","title":"XStream can cause a Denial of Service","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 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.","provenance":"source","from":"CVE.org"},"summary":{"text":"The XStream Java library (product: xstream, from vendor x-stream) contains a flaw in its XML deserialization handling that allows a crafted input stream to consume a large amount of CPU time, with the risk greater for systems that rely on its default blacklist rather than a whitelist limited to the required types. A remote attacker with no authentication, no required user interaction, and only network access to a service that deserializes untrusted input can exhaust CPU on the target and cause denial of service.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T07:13:14Z"},"cvss":{"score":7.5,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.77801,"percentile":0.99568,"date":"2026-10-29","provenance":"source"},"kev":null,"vulncheckKev":null,"exploited":false,"otx":{"pulseCount":0,"pulses":[],"provenance":"machine"},"cwes":[{"id":"CWE-400","name":"Uncontrolled Resource Consumption"},{"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-2p3x-qw9c-25hh","tags":["x_refsource_CONFIRM"]},{"url":"https://x-stream.github.io/CVE-2021-21341.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://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-2p3x-qw9c-25hh"],"provenance":"source"}],"advisories":[{"id":"GHSA-2p3x-qw9c-25hh","url":"https://github.com/advisories/GHSA-2p3x-qw9c-25hh","severity":"HIGH","ecosystem":"Maven","package":"com.thoughtworks.xstream:xstream","vulnerableRanges":["<1.4.16"],"patched":["1.4.16"],"provenance":"source","from":"GHSA"}],"euvd":{"id":"EUVD-2021-0586","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-0586","exploited":false,"exploitedSince":null,"provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":1,"earliest":"2021-05-09","earliestUrl":"https://github.com/s-index/CVE-2021-21341","repos":[{"name":"s-index/CVE-2021-21341","url":"https://github.com/s-index/CVE-2021-21341","stars":0,"created":"2021-05-09"}]},"first":{"date":"2021-05-09","source":"PoC-in-GitHub","url":"https://github.com/s-index/CVE-2021-21341"},"provenance":"source"},"exploitRefs":[],"flow":[],"timeline":[{"date":"2021-03-22","kind":"published","label":"Published (CVE.org)","url":"https://www.cve.org/CVERecord?id=CVE-2021-21341","provenance":"source"},{"date":"2021-05-09","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/s-index/CVE-2021-21341","provenance":"source"}],"speed":{"daysToPublicExploit":48,"firstExploitFrom":"PoC-in-GitHub","daysToKev":null},"priority":{"score":30.2,"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":19.91,"detail":"percentile 0.9957"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"1 PoC-in-GitHub repo"},{"name":"Mentioned in OTX pulses","points":0.0,"detail":"0 pulses"},{"name":"CVSS severity","points":5.25,"detail":"base score 7.5"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}