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Vulnerability record · CVE-2026-2603 · published 18 March 2026

CVE-2026-2603: Redhat build of keycloak missing authentication for critical function vulnerability

Redhat · Build Of Keycloak

A flaw was found in Keycloak. A remote attacker could bypass security controls by sending a valid SAML response from an external Identity Provider (IdP) to the Keycloak SAML endpoint for IdP-initiated broker logins. This allows the attacker to complete broker logins even when the SAML Identity Provider is disabled, leading to unauthorized authentication.

8.1 CVSS 3.1 High EPSS 0.72% · top 47.9% CWE-306 · Missing authentication for critical function
8.1CVSS 3.1 base score
0.72%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
14References, 3 tagged exploit
18 Aug 2026Last modified by NVD

Description

A flaw was found in Keycloak. A remote attacker could bypass security controls by sending a valid SAML response from an external Identity Provider (IdP) to the Keycloak SAML endpoint for IdP-initiated broker logins. This allows the attacker to complete broker logins even when the SAML Identity Provider is disabled, leading to unauthorized authentication.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://access.redhat.com/errata/RHSA-2026:3925 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3926 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3947 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3948 Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-2603 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2440300 ExploitIssue TrackingVendor Advisory
https://access.redhat.com/errata/RHSA-2026:3925 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3926 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3947 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3948 Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-2603 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2440300 ExploitIssue TrackingVendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2440300 ExploitIssue TrackingVendor Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2603.json Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2026-16442Redhat build of keycloak origin validation error vulnerabilityA flaw was found in the SAML broker component of Keycloak, which is used to manage identity federation and user authentication. The issue occurs beca…EPSS 0.31%9.1CVE-2026-16443Redhat build of keycloak improper verification of cryptographic signature vulnerabilityA flaw was found in the SAML metadata import functionality of the keycloak-services component, which is the core engine for identity brokering in Red…EPSS 0.26%8.8CVE-2026-15572Redhat build of keycloak type confusion vulnerabilityA flaw was found in Keycloak's Dynamic Client Registration (DCR) security policy management. The "Allowed Protocol Mapper Types" policy, which restri…EPSS 0.65%8.8CVE-2026-9704Redhat build of keycloak vulnerabilityA flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web…EPSS 0.59%8.8CVE-2026-3047Redhat build of keycloak vulnerabilityA flaw was found in org.keycloak.broker.saml. When a disabled Security Assertion Markup Language (SAML) client is configured as an Identity Provider …EPSS 0.86%8.8CVE-2023-6787Redhat build of keycloak improper authentication vulnerabilityA flaw was found in Keycloak that occurs from an error in the re-authentication mechanism within org.keycloak.authentication. This flaw allows hijack…EPSS 0.74%8.1CVE-2026-18967Redhat build of keycloak authentication bypass by capture-replay vulnerabilityA 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…EPSS 0.23%8.1CVE-2026-16102Redhat build of keycloak improper access control vulnerabilityA flaw was found in the Dynamic Client Registration (DCR) component of Keycloak, an identity and access management solution. The default DCR policy f…EPSS 0.46%

Source: NIST National Vulnerability Database (record CVE-2026-2603), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.