{"cve":"CVE-2023-6563","nvd":{"published":"2023-12-14T18:15:45.540","modified":"2026-09-22T04:17:56.693","status":"Modified","description":"An unconstrained memory consumption vulnerability was discovered in Keycloak. It can be triggered in environments which have millions of offline tokens (> 500,000 users with each having at least 2 saved sessions). If an attacker creates two or more user sessions and then open the \"consents\" tab of the admin User Interface, the UI attempts to load a huge number of offline client sessions leading to excessive memory and CPU consumption which could potentially crash the entire system.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H","score":7.7},"cwes":["CWE-770"],"references":["https://access.redhat.com/errata/RHSA-2023:7854","https://access.redhat.com/errata/RHSA-2023:7855","https://access.redhat.com/errata/RHSA-2023:7856","https://access.redhat.com/errata/RHSA-2023:7857","https://access.redhat.com/errata/RHSA-2023:7858"],"products":["redhat:keycloak","redhat:openshift_container_platform","redhat:openshift_container_platform_for_ibm_linuxone","redhat:openshift_container_platform_for_power","redhat:single_sign-on"],"source":"nvd","synced_at":"2026-10-19T21:42:34.585441961+00:00"},"epss":{"cve":"CVE-2023-6563","score":0.01239,"percentile":0.69153,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-54f3-c6hg-865h","url":"https://osv.dev/vulnerability/GHSA-54f3-c6hg-865h","summary":"Allocation of Resources Without Limits in Keycloak","modified":"2024-02-16T08:20:54.668090Z","packages":[{"ecosystem":"Maven","name":"org.keycloak:keycloak-model-jpa","purl":"pkg:maven/org.keycloak/keycloak-model-jpa","ranges":["<21.0.0"],"fixed":["21.0.0"]}]}],"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."]}