{"id":"CVE-2025-12543","details":"A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.","aliases":["GHSA-j382-5jj3-vw4j"],"modified":"2026-04-10T05:20:57.552975Z","published":"2026-01-07T17:15:55.093Z","related":["CGA-rcjr-v892-2qf8"],"references":[{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:0383"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:0384"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:0386"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:3890"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:3892"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:4915"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:4917"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:3889"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:3891"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:4916"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:4924"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2025-12543"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2408784"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/undertow-io/undertow","events":[{"introduced":"0"},{"fixed":"44e259c325f90432313bf107c0c358a24be805b0"},{"introduced":"ddb772c84f8ee5ce7a803c883df313c1e2353e8a"},{"fixed":"791c90859980f808e3ce1e258bff78990df7ca95"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"2.2.39"},{"introduced":"2.3.0"},{"fixed":"2.3.21"}]}}],"versions":["1.0.0.Alpha1","1.0.0.Alpha10","1.0.0.Alpha11","1.0.0.Alpha12","1.0.0.Alpha13","1.0.0.Alpha14","1.0.0.Alpha15","1.0.0.Alpha16","1.0.0.Alpha17","1.0.0.Alpha18","1.0.0.Alpha19","1.0.0.Alpha2","1.0.0.Alpha20","1.0.0.Alpha21","1.0.0.Alpha22","1.0.0.Alpha3","1.0.0.Alpha4","1.0.0.Alpha5","1.0.0.Alpha6","1.0.0.Alpha7","1.0.0.Alpha8","1.0.0.Alpha9","1.0.0.Beta1","1.0.0.Beta10","1.0.0.Beta11","1.0.0.Beta12","1.0.0.Beta13","1.0.0.Beta14","1.0.0.Beta15","1.0.0.Beta16","1.0.0.Beta17","1.0.0.Beta18","1.0.0.Beta19","1.0.0.Beta2","1.0.0.Beta20","1.0.0.Beta21","1.0.0.Beta22","1.0.0.Beta23","1.0.0.Beta24","1.0.0.Beta25","1.0.0.Beta26","1.0.0.Beta27","1.0.0.Beta28","1.0.0.Beta29","1.0.0.Beta3","1.0.0.Beta30","1.0.0.Beta31","1.0.0.Beta32","1.0.0.Beta33","1.0.0.Beta4","1.0.0.Beta5","1.0.0.Beta6","1.0.0.Beta7","1.0.0.Beta8","1.0.0.Beta9","1.0.0.CR1","1.0.0.CR2","1.0.0.CR3","1.0.0.CR4","1.0.0.Final","1.0.1.Final","1.0.2.Final","1.0.3.Final","1.1.0.Beta1","1.1.0.Beta2","1.1.0.Beta3","1.1.0.Beta4","1.1.0.Beta5","1.1.0.Beta6","1.1.0.Beta7","1.1.0.Beta8","1.2.0.Beta1","1.2.0.Beta10","1.2.0.Beta2","1.2.0.Beta3","1.2.0.Beta4","1.2.0.Beta5","1.2.0.Beta6","1.2.0.Beta7","1.2.0.Beta8","1.2.0.Beta9","1.2.0.CR1","1.2.0.Final","1.2.1.Final","1.2.2.Final","1.2.3.Final","1.2.4.Final","1.3.0.Beta1","1.3.0.Beta10","1.3.0.Beta11","1.3.0.Beta12","1.3.0.Beta13","1.3.0.Beta2","1.3.0.Beta3","1.3.0.Beta4","1.3.0.Beta5","1.3.0.Beta6","1.3.0.Beta7","1.3.0.Beta8","1.3.0.Beta9","1.3.0.CR1","1.3.0.CR2","1.3.0.CR3","1.3.0.Final","1.3.1.Final","1.3.2.Final","1.3.3.Final","2.0.0.Alpha1","2.0.0.Beta1","2.0.0.Final","2.0.1.Final","2.0.10.Final","2.0.11.Final","2.0.12.Final","2.0.13.Final","2.0.14.Final","2.0.15.Final","2.0.16.Final","2.0.17.Final","2.0.2.Final","2.0.20.Final","2.0.21.Final","2.0.22.Final","2.0.23.Final","2.0.24.Final","2.0.25.Final","2.0.26.Final","2.0.27.Final","2.0.28.Final","2.0.29.Final","2.0.3.Final","2.0.4.Final","2.0.5.Final","2.0.6.Final","2.0.7.Final","2.0.8.Final","2.0.9.Final","2.1.0.Final","2.1.1.Final","2.1.2.Final","2.1.3.Final","2.1.4.Final","2.2.0.Final","2.2.1.Final","2.2.10.Final","2.2.11.Final","2.2.12.Final","2.2.13.Final","2.2.14.Final","2.2.15.Final","2.2.16.Final","2.2.17.Final","2.2.18.Final","2.2.19.Final","2.2.2.Final","2.2.20.Final","2.2.21.Final","2.2.22.Final","2.2.23.Final","2.2.24.Final","2.2.25.Final","2.2.26.Final","2.2.27.Final","2.2.28.Final","2.2.3.Final","2.2.30.Final","2.2.31.Final","2.2.32.Final","2.2.33.Final","2.2.34.Final","2.2.35.Final","2.2.36.Final","2.2.37.Final","2.2.38.Final","2.2.4.Final","2.2.5.Final","2.2.6.Final","2.2.7.Final","2.2.8.Final","2.2.9.Final","2.3.0.Final","2.3.1.Final","2.3.10.Final","2.3.11.Final","2.3.12.Final","2.3.13.Final","2.3.14.Final","2.3.15.Final","2.3.16.Final","2.3.17.Final","2.3.18.Final","2.3.19.Final","2.3.2.Final","2.3.20.Final","2.3.3.Final","2.3.4.Final","2.3.5.Final","2.3.6.Final","2.3.7.Final","2.3.8.Final","2.3.9.Final"],"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"0"},{"fixed":"4.14.4"}]},{"events":[{"introduced":"0"},{"last_affected":"8.0"}]},{"events":[{"introduced":"0"},{"last_affected":"7.0.0"}]},{"events":[{"introduced":"8.0"},{"fixed":"8.0.12"}]},{"events":[{"introduced":"8.1.0"},{"fixed":"8.1.3"}]},{"events":[{"introduced":"0"},{"last_affected":"7.0.0"}]},{"events":[{"introduced":"0"},{"last_affected":"7.0"}]},{"events":[{"introduced":"0"},{"last_affected":"7.0"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-12543.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"}]}