Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Network-reachable endpoint with no privileges on Keycloak yields AV:N/PR:N; account takeover gives C:H/I:H, but there is no direct availability impact so A:N (vs vendor A:H).
Primary rating from Vendor (redhat).
CVSS VectorNVD
Lifecycle Timeline
6DescriptionNVD
A flaw was found in the SAML broker component of Keycloak, which is used to manage identity federation and user authentication. The issue occurs because the IdP-initiated Single Sign-On endpoint fails to check if a provider is restricted to account linking only. This allows an attacker with control over a linked upstream identity to bypass login restrictions and gain full access to a local user account.
AnalysisAI
Account takeover in Keycloak (Red Hat build of Keycloak, Red Hat Single Sign-On 7) arises because the IdP-initiated SAML SSO endpoint does not verify whether an upstream identity provider is restricted to account-linking-only mode. An attacker who controls a linked upstream identity can drive that endpoint to complete a full login rather than a mere link operation, seizing complete access to the corresponding local user account. Red Hat has shipped fixes; there is no public exploit identified at time of analysis and EPSS exploitation probability is low (0.19%).
Technical ContextAI
Keycloak is a widely used open-source identity and access management server that brokers external identity providers (IdPs) for federation and single sign-on. The affected code path is the SAML broker's IdP-initiated SSO endpoint, which processes unsolicited SAML responses pushed from an external IdP. Administrators can configure a broker provider so that it may only be used to link an external identity to an existing local account ('account linking only'), not to authenticate and establish a full session. The flaw is a CWE-346 origin/authorization-context validation failure: the endpoint fails to enforce that account-linking-only restriction, so a SAML assertion that should only be permitted to link is instead honored as a full authentication. Affected packages per the CPE data include red_hat_build_of_keycloak, red_hat_single_sign-on_7, and the Keycloak-derived components shipped with Red Hat Data Grid 8 and the JBoss EAP Expansion Pack.
RemediationAI
Apply the vendor-released patches: update the Red Hat build of Keycloak to 26.4 (package 26.4-22 or 26.4.14-1) or 26.6 (package 26.6-11 or 26.6.5-1), and apply the corresponding RHSA errata for the affected products (https://access.redhat.com/errata/RHSA-2026:50846, RHSA-2026:50847, RHSA-2026:50848, and RHSA-2026:50849). If immediate patching is not possible, reduce exposure by auditing all SAML broker identity providers configured as account-linking-only and temporarily disabling those providers or the IdP-initiated SSO flow for them, accepting the trade-off that users relying on those links will lose that federation path until patched; additionally restrict or firewall the SAML broker endpoint to trusted networks, and review recently created or reactivated account links for signs of abuse. Consult the Red Hat CVE page (https://access.redhat.com/security/cve/CVE-2026-16442) for the authoritative fixed builds before deploying.
More in Red Hat Build Of Keycloak
View allAccount takeover in Red Hat Build of Keycloak allows an unauthenticated attacker to abuse the reset-credentials flow in
Authentication bypass in Red Hat Build of Keycloak (and Red Hat Single Sign-On 7) lets an unauthenticated attacker forge
Privilege escalation in Red Hat Build of Keycloak's Dynamic Client Registration (DCR) grants an attacker with low-privil
Mismatched handling of the HTTP/1 absolute-form request authority in Red Hat build of Quarkus and other affected Red Hat
Authorization bypass in the Keycloak Policy Enforcer allows any authenticated user to circumvent all enforced access con
URI normalization bypass in Keycloak's Authorization Services PathMatcher allows authenticated low-privilege users to re
Privilege escalation in Keycloak's Dynamic Client Registration (DCR) component allows attackers with standard user accou
Token exchange in Keycloak bypasses Google Workspace domain allowlist restrictions, enabling any valid Google account ho
Signature-verification bypass in Keycloak (and Red Hat's Keycloak-based products such as Red Hat Single Sign-On 7 and Re
Tenant-restriction bypass in Keycloak's Microsoft identity provider integration allows attackers holding any valid Micro
Session hijacking via SAML assertion replay in Keycloak's SAML broker component allows adjacent-network attackers to aut
Open redirect in Red Hat build of Keycloak permits remote attackers to send victims to attacker-controlled hosts by abus
Same weakness CWE-346 – Origin Validation Error
View allSame technique Authentication Bypass
View allVendor StatusVendor
Share
External POC / Exploit Code
Leaving vuln.today
EUVD-2026-53395
GHSA-vj6m-hv26-qx79