{"cve":"CVE-2020-26258","nvd":{"published":"2020-12-16T01:15:12.333","modified":"2026-10-07T19:17:17.510","status":"Analyzed","description":"XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.15, a Server-Side Forgery Request vulnerability can be activated when unmarshalling. The vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.15. The reported vulnerability does not exist if running Java 15 or higher. No user is affected who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability. Users of XStream 1.4.14 or below who still want to use XStream default blacklist can use a workaround described in more detailed in the referenced advisories.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N","score":7.7},"cwes":["CWE-918"],"references":["https://github.com/x-stream/xstream/security/advisories/GHSA-4cch-wxpw-8p28","https://lists.apache.org/thread.html/r97993e3d78e1f5389b7b172ba9f308440830ce5f051ee62714a0aa34@%3Ccommits.struts.apache.org%3E","https://lists.debian.org/debian-lts-announce/2020/12/msg00042.html","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP","https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7"],"products":["apache:struts","debian:debian_linux","fedoraproject:fedora","xstream:xstream"],"source":"nvd","synced_at":"2026-10-19T21:12:09.559580076+00:00"},"epss":{"cve":"CVE-2020-26258","score":0.81817,"percentile":0.99643,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-4cch-wxpw-8p28","url":"https://osv.dev/vulnerability/GHSA-4cch-wxpw-8p28","summary":"Server-Side Forgery Request can be activated unmarshalling with XStream","modified":"2026-09-10T03:49:00.699163166Z","packages":[{"ecosystem":"Maven","name":"com.thoughtworks.xstream:xstream","purl":"pkg:maven/com.thoughtworks.xstream/xstream","ranges":["<1.4.15"],"fixed":["1.4.15"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}