{"id":"CVE-2026-9803","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-9803","summary":"Keycloak has an Out-of-bounds Read","details":"A flaw was found in Keycloak's ClientRegistrationAuth component. A remote unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with a malformed 'Authorization: Bearer' header to any client registration endpoint. This can lead to an ArrayIndexOutOfBoundsException, causing the server to return an HTTP 500 error and resulting in a Denial of Service (DoS) for the affected service.","published":"2026-05-28T06:31:10Z","modified":"2026-07-01T21:45:23.127828861Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.00417,"percentile":0.34494,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"org.keycloak:keycloak-services","fixedVersion":null},{"ecosystem":"Maven","name":"org.keycloak:keycloak-services","fixedVersion":"26.6.3"}],"fix":{"url":"https://github.com/keycloak/keycloak/pull/49500","label":"keycloak/keycloak#49500"},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-9803"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/issues/49433"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/pull/49500"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/pull/49617"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/pull/49618"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/commit/2b8692499e907e6205be0bd9c8a4da5d46f6ca30"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/commit/3fc06909cc93eb5c4739a712fa350de625812e04"},{"type":"WEB","url":"https://github.com/keycloak/keycloak/commit/ef06df91d344c7e99fcb82987ef6adb854f30789"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:25097"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:25098"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:30049"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:30050"},{"type":"WEB","url":"https://access.redhat.com/security/cve/CVE-2026-9803"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2482465"},{"type":"PACKAGE","url":"https://github.com/keycloak/keycloak"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-01T21:45:23.127828861Z"}}