CVE-2026-4634

HIGH EPSS 39.7%

Published Apr 2, 20262mo ago · Modified Jun 17, 20261w ago

7.5 CVSS 3.1

High

Published Apr 2, 2026 2mo ago

Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score

7.5

Exploitability

3.9

Impact

3.6

Vector string

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector Network

Attack Complexity Low

Privileges Required None

User Interaction None

Scope Unchanged

Confidentiality None

Integrity None

Availability High

Threat Intelligence

EPSS Exploit Probability

39.7% percentile

Exploit & Patch Status

No Known Exploit

No Patch Available

Weaknesses 1

CWE-1050

Affected Products 5

Vendor	Product	Version	Range
redhat	build_of_keycloak	*	any
redhat	build_of_keycloak	26.2	any
redhat	build_of_keycloak	26.2.15	any
redhat	build_of_keycloak	26.4	any
redhat	build_of_keycloak	26.4.11	any

References 6

access.redhat.com https://access.redhat.com/errata/RHSA-2026:6475

Vendor Advisory
access.redhat.com https://access.redhat.com/errata/RHSA-2026:6476

Vendor Advisory
access.redhat.com https://access.redhat.com/errata/RHSA-2026:6477

Vendor Advisory
access.redhat.com https://access.redhat.com/errata/RHSA-2026:6478

Vendor Advisory
access.redhat.com https://access.redhat.com/security/cve/CVE-2026-4634

Vendor Advisory
bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2450250

Issue TrackingVendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.