CVE-2026-4634
Keycloak: Application-Level DoS via Scope Processing
7.5
HIGH
CVSS 3.1
EPSS 0.02%
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.
How to fix CVE-2026-4634
To remediate CVE-2026-4634, upgrade the affected package to a fixed version below.
- —upgrade to 26.5.7 or later
Is CVE-2026-4634 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 26.5.7
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |