CVE-2026-4634

Name: CVE-2026-4634
Creator: NVD / NIST
Published: 2026-04-02T13:16:27.027+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.51%

Last modified Jun 17, 2026

CVE-2026-4634 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.51% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.51%

39.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-1050

Affected Software

Vendor	Product	Versions
Redhat	Build Of Keycloak	All versions
Redhat	Build Of Keycloak	26.2
Redhat	Build Of Keycloak	26.2.15
Redhat	Build Of Keycloak	26.4
Redhat	Build Of Keycloak	26.4.11

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 Tracking, Vendor Advisory

Timeline

Published: Apr 2, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-4634?

How severe is CVE-2026-4634?

CVE-2026-4634 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.51% probability of exploitation in the next 30 days.

How do I fix CVE-2026-4634?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-4634?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST