CVE-2026-4634 — HIGH (7.5) — White Hats Nepal

Vulnerability 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 Score

7.5

HIGH

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

Affected Products

Vendor	Product	Versions
Redhat	Build Of Keycloak	-

Related Weaknesses (CWE)

CWE-1050

References

https://access.redhat.com/errata/RHSA-2026:6475Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:6476Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:6477Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:6478Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-4634Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2450250Issue TrackingVendor Advisory

FAQ

What is CVE-2026-4634?

CVE-2026-4634 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 (OID...

How severe is CVE-2026-4634?

CVE-2026-4634 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-4634?

Check the references section above for vendor advisories and patch information. Affected products include: Redhat Build Of Keycloak.