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High 7.5Published Apr 2, 2026

CVE-2026-4634Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters

Updated under an hour ago ()

Does this affect you?

It affects Red Hat build of Keycloak 26.2 and 3 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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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
7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE)
CWE-1050
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
redhat
NVD analysis
Modified
Record last updated
Oct 6, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
from 26.2.15-1 not affected
CNA record
Red Hat Red Hat Single Sign-On 7.6.13
redhat:red_hat_single_sign_on
7.6
CNA record
from 7.6-85 not affected
CNA record
from 26.2.15-1 not affected
CISA ADP
redhat build_of_keycloak
redhat:build_of_keycloak
all versions; 26.2; 26.2.15; 26.4; 26.4.11
NVD

References

References

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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