Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters (Red Hat Red Hat build of Keycloak 26.2)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.64 % · percentile 51 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- redhat
- NVD status
- Modified
Description
A flaw was found in Keycloak. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with an excessively long scope parameter to the OpenID Connect (OIDC) token endpoint. This leads to high resource consumption and prolonged processing times, ultimately resulting in a Denial of Service (DoS) for the Keycloak server.
Weaknesses (CWE)
- CWE-1050 — Excessive Platform Resource Consumption within a Loop
References
- https://access.redhat.com/errata/RHSA-2026:6475
- https://access.redhat.com/errata/RHSA-2026:6476
- https://access.redhat.com/errata/RHSA-2026:6477
- https://access.redhat.com/errata/RHSA-2026:6478
- https://access.redhat.com/errata/RHSA-2026:76128
- https://access.redhat.com/errata/RHSA-2026:76129
- https://access.redhat.com/errata/RHSA-2026:76130
- https://access.redhat.com/errata/RHSA-2026:76132
- https://access.redhat.com/errata/RHSA-2026:76134
- https://access.redhat.com/security/cve/CVE-2026-4634
- https://bugzilla.redhat.com/show_bug.cgi?id=2450250
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4634.json
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | redhat |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | redhat-SADP |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · secalert@redhat.com (Secondary) |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary) |
Advisories
- GHSA-h4wv-g838-66g3 — Keycloak: Application-Level DoS via Scope Processing
European references
- ENISA EUVD · EUVD-2026-18212
- GCVE · GCVE-0-2026-4634
Affected configurations (NVD CPE)
cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:text-only:*:*:*cpe:2.3:a:redhat:build_of_keycloak:26.2:*:*:*:text-only:*:*:*cpe:2.3:a:redhat:build_of_keycloak:26.2.15:*:*:*:text-only:*:*:*cpe:2.3:a:redhat:build_of_keycloak:26.4:*:*:*:text-only:*:*:*cpe:2.3:a:redhat:build_of_keycloak:26.4.11:*:*:*:text-only:*:*:*
Affected products
| Product | Versions |
|---|---|
| Red Hat · Red Hat build of Keycloak 26.2 | unaffected 26.2.15-1 < * |
| Red Hat · Red Hat build of Keycloak 26.2 | unaffected 26.2-18 < * |
| Red Hat · Red Hat build of Keycloak 26.2 | unaffected 26.2-18 < * |
| Red Hat · Red Hat build of Keycloak 26.2.15 | |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4.11-1 < * |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4-14 < * |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4-14 < * |
| Red Hat · Red Hat build of Keycloak 26.4.11 | |
| Red Hat · Red Hat Single Sign-On 7.6.13 | |
| Red Hat · Red Hat Single Sign-On 7.6 for RHEL 7 | unaffected 0:18.0.20-1.redhat_00001.1.el7sso < * |
| Red Hat · Red Hat Single Sign-On 7.6 for RHEL 8 | unaffected 0:18.0.20-1.redhat_00001.1.el8sso < * |
| Red Hat · Red Hat Single Sign-On 7.6 for RHEL 9 | unaffected 0:18.0.20-1.redhat_00001.1.el9sso < * |
| Red Hat · RHEL-8 based Middleware Containers | unaffected 7.6-85 < * |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |