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CVE-2026-4634

Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters

Published: Apr 2, 2026Updated: Apr 16, 2026 Sources: CVE List NVDCWE-1050
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.5%
Top 60.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-1050

Affected Products

build of keycloakredhat
On-prem
Security Products / identity-access-mgmt
Red Hat build of Keycloak 26.2Red Hat
On-prem
Operating Systems / linux-distro
Red Hat build of Keycloak 26.2.15Red Hat
On-prem
Operating Systems / linux-distro
Red Hat build of Keycloak 26.4Red Hat
On-premWeb App
Web & CMS Plugins
Red Hat build of Keycloak 26.4.11Red Hat
On-prem
Operating Systems / linux-distro
redhatcommercialUSOperating Systemsaka red hat
red hatcommercialUSOperating Systemsaka red hat

Exploitability

Official Patch Available
Workaround Available

References

https://access.redhat.com/errata/RHSA-2026:6475
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:6476
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:6477
access.redhat.com
and 3 more references View all →

Timeline

Published
Apr 2, 2026
Last Updated
Apr 16, 2026

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