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.

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Fixes

Solution

No solution given by the vendor.


Workaround

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

History

Fri, 07 Aug 2026 09:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat build Of Keycloak
Redhat jboss Enterprise Application Platform Expansion Pack
Redhat single Sign-on
Vendors & Products Redhat build Of Keycloak
Redhat jboss Enterprise Application Platform Expansion Pack
Redhat single Sign-on

Thu, 06 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 06 Aug 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Thu, 06 Aug 2026 06:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Keycloak-services: keycloak-services: saml onetimeuse assertion replay in idp-initiated broker flow
First Time appeared Redhat
Redhat build Keycloak
Redhat jbosseapxp
Redhat red Hat Single Sign On
Weaknesses CWE-294
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:jbosseapxp
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat build Keycloak
Redhat jbosseapxp
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 6.4, 'vector': 'CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-08-06T17:31:57.855Z

Reserved: 2026-08-05T15:22:29.997Z

Link: CVE-2026-18967

cve-icon Vulnrichment

Updated: 2026-08-06T17:25:22.113Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-07-31T14:42:39Z

Links: CVE-2026-18967 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-07T09:15:07Z

Weaknesses