CVE-2026-18967 MEDIUM

CVE-2026-18967: Keycloak-services: keycloak-services: saml onetimeuse assertion replay in idp-initiated broker flow

Vendor Red Hat
Product Red Hat Build of Keycloak
Weakness CWE-294
Published August 6, 2026
Last update August 6, 2026

CVSS base score

6.4/10
Attack vector Adjacent
Attack complexity High
Privileges required None
User interaction Required
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

A flaw was found in the SAML broker component of Keycloak, an identity and access management solution. When configured as a SAML broker using the IdP-Initiated flow, Keycloak fails to enforce the OneTimeUse condition in SAML assertions. This allows an attacker who captures a valid, unused assertion to replay it multiple times. Successful exploitation could allow an attacker to hijack a user's session and gain unauthorized access to the system as that user.

Key dates

02Disclosure timeline

August 6, 2026 CVE published
August 6, 2026 Record updated