CVE-2026-18967 Keycloak-services: keycloak-services: saml onetimeuse assertion replay in idp-initiated broker flow
Attackers can replay SAML assertions in IdP-initiated flows to hijack user sessions and gain unauthorized access.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-18967?
CVE-2026-18967 is a medium-severity authentication bypass vulnerability in Redhat Build of Keycloak, published on 6 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-294
Which versions are affected by CVE-2026-18967?
It affects 2 products.
Products include Redhat Build of Keycloak, Redhat Jboss Enterprise Application Platform Expansion Pack.
How do I fix CVE-2026-18967?
No fix has been published for CVE-2026-18967 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-18967 being exploited?
There is no known exploitation of CVE-2026-18967 in the wild and no public exploit code.
Other vulnerabilities in Redhat Build of Keycloak
- CVE-2026-15572 Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation
- CVE-2026-3047 Keycloak SAML Broken has Authentication Bypass by Primary Weakness
- CVE-2026-15573 Keycloak-services: keycloak-services: authorization bypass via unnormalized uri matching in pathmatcher
- CVE-2026-16102 Keycloak-services: keycloak-services: default dcr policy allows role forgery via user property mappers
- CVE-2026-1609 Org.keycloak/keycloak-quarkus-server: keycloak: unauthorized access via jwt authorization grant with disabled users
Sources
Also known as GHSA-fghp-hcwh-75j2.