high7.5
CVE-2026-4634
Keycloak: Application-Level DoS via Scope Processing
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| maven | org.keycloak:keycloak-services | < 26.5.7 | 26.5.7 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Redhat | Build Of Keycloak | All versions Versions 26.2, 26.2.15, 26.4, 26.4.11 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- 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
- https://github.com/advisories/GHSA-h4wv-g838-66g3
- https://nvd.nist.gov/vuln/detail/CVE-2026-4634
- https://github.com/keycloak/keycloak/issues/47716
- https://github.com/keycloak/keycloak/commit/b455ee4f28abb6f2120aff72fd179589cc5267a0