CVE-2026-18215: medium-severity vulnerability in Red Hat build of Keycloak 26.6
Keycloak-services: keycloak-services: microsoft external access-token exchange bypasses configured tenant
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.8epss 0.4%
Keycloak provides a way to let users log in using Microsoft accounts while restricting access to a specific organization (tenant). A flaw was discovered where this restriction is ignored when using the token exchange feature. This means an attacker with a valid Microsoft token from a completely different organization could gain access to the Keycloak realm, potentially accessing sensitive data or performing unauthorized actions.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Affected products
Red Hat · Red Hat build of Keycloak 26.6Red Hat · Red Hat build of Keycloak 26.6.7Red Hat · Red Hat Data Grid 8Red Hat · Red Hat JBoss Enterprise Application Platform Expansion PackRed Hat · Red Hat Single Sign-On 7Related CVEs — Red Hat build of Keycloak 26.6
In the same product, most dangerous first.
CVE-2026-18963CRITICALKeycloak-services: keycloak-services: unauthenticated account takeover via reset-credentials flow bypassEPSS 6.6%CVE-2024-1635HIGHUndertow: out-of-memory error after several closed connections with wildfly-http-client protocolEPSS 4.6%CVE-2023-5685HIGHXnio: stackoverflowexception when the chain of notifier states becomes problematically bigEPSS 3.5%CVE-2024-5971HIGHUndertow: response write hangs in case of java 17 tlsv1.3 newsessionticketEPSS 2.9%CVE-2026-93567HIGHIo.netty/netty-codec-http2: http/1 authority-form connect is translated to malformed http/2 connect with host-controlled :authorityEPSS 2.9%CVE-2023-3223HIGHUndertow: outofmemoryerror due to @multipartconfig handlingEPSS 2.7%