SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2026-4634

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.

HIGH 7.5EPSS 0.63%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.63%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 3.1
7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
0.63% probability · 50th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-1050
Affected
redhat/build of keycloak
Source
secalert@redhat.com
EPSS trend
0%3%5%27 October 2026: 0.63%27 October 202627 October 2026

EPSS 0.6% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.