{"id":"CVE-2021-39152","published":"2021-08-23T18:20:10Z","modified":"2026-10-07T20:01:09Z","title":"A Server-Side Forgery Request vulnerability in XStream via HashMap unmarshaling","vendor":"x-stream","product":"xstream","tier":"core","eol":null,"affectedVersions":[{"vendor":"x-stream","product":"xstream","versions":["< 1.4.18"]}],"description":{"text":"XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream with a Java runtime version 14 to 8. 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](https://x-stream.github.io/security.html#framework), you will have to use at least version 1.4.18.","provenance":"source","from":"CVE.org"},"summary":{"text":"A Server-Side Request Forgery flaw in XStream's HashMap unmarshaling, which is the XML-to-object deserialization component of the XStream serialization library.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T13:44:03Z"},"cvss":{"score":8.5,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.11377,"percentile":0.95992,"date":"2026-10-31","provenance":"source"},"kev":null,"vulncheckKev":{"dateAdded":"2026-02-14","exploitedFirstSeen":"2026-02-14","ransomware":false,"evidence":[{"url":"https://www.labs.greynoise.io/grimoire/2026-02-13-weekly-oast-report/","date":"2026-02-14"}],"evidenceTotal":1,"provenance":"source"},"exploited":true,"otx":null,"cwes":[{"id":"CWE-502","name":"Deserialization of Untrusted Data"},{"id":"CWE-918","name":"Server-Side Request Forgery"}],"references":[{"url":"https://github.com/x-stream/xstream/security/advisories/GHSA-xw4p-crpj-vjx2","tags":["x_refsource_CONFIRM"]},{"url":"https://x-stream.github.io/CVE-2021-39152.html","tags":["x_refsource_MISC"]},{"url":"https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html","tags":["mailing-list","x_refsource_MLIST"]},{"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://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"]},{"url":"https://security.netapp.com/advisory/ntap-20210923-0003/","tags":["x_refsource_CONFIRM"]},{"url":"https://www.oracle.com/security-alerts/cpuapr2022.html","tags":["x_refsource_MISC"]},{"url":"https://www.oracle.com/security-alerts/cpujul2022.html","tags":["x_refsource_MISC"]}],"techniques":[],"reports":[],"affected":[{"ecosystem":"Maven","package":"com.thoughtworks.xstream:xstream","vulnerableRanges":["<1.4.18"],"patched":["1.4.18"],"from":["GHSA-xw4p-crpj-vjx2"],"provenance":"source"}],"advisories":[{"id":"GHSA-xw4p-crpj-vjx2","url":"https://github.com/advisories/GHSA-xw4p-crpj-vjx2","severity":"HIGH","ecosystem":"Maven","package":"com.thoughtworks.xstream:xstream","vulnerableRanges":["<1.4.18"],"patched":["1.4.18"],"provenance":"source","from":"GHSA"}],"euvd":{"id":"EUVD-2021-1941","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-1941","exploited":false,"exploitedSince":null,"provenance":"source"},"exploits":[],"exploitSources":{"nuclei":[{"id":"CVE-2021-39152","name":"XStream <1.4.18 - Server-Side Request Forgery","severity":"high","path":"http/cves/2021/CVE-2021-39152.yaml","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-39152.yaml"}],"provenance":"source"},"exploitRefs":[],"flow":[],"timeline":[{"date":"2021-08-23","kind":"published","label":"Published (CVE.org)","url":"https://www.cve.org/CVERecord?id=CVE-2021-39152","provenance":"source"},{"date":"2026-02-14","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.labs.greynoise.io/grimoire/2026-02-13-weekly-oast-report/","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":null},"priority":{"score":70.1,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in VulnCheck KEV"},{"name":"Recent KEV listing","points":5.0,"detail":"added 260 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":19.2,"detail":"percentile 0.9599"},{"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":5.95,"detail":"base score 8.5"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}