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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.

PUBLISHED Reserved 2026-02-16 | Published 2026-03-18 | Updated 2026-03-18 | Assigner redhat




HIGH: 8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Problem types

Missing Authentication for Critical Function

Product status

Default status
affected

26.2.14-1 (rpm) before *
unaffected

Default status
affected

26.2-16 (rpm) before *
unaffected

Default status
affected

26.2-16 (rpm) before *
unaffected

Default status
unaffected

Default status
affected

26.4.10-1 (rpm) before *
unaffected

Default status
affected

26.4-12 (rpm) before *
unaffected

Default status
affected

26.4-12 (rpm) before *
unaffected

Default status
unaffected

Timeline

2026-02-16:Reported to Red Hat.
2026-03-05:Made public.

Credits

Red Hat would like to thank Joy Gilbert and Reynaldo Immanuel for reporting this issue.

References

bugzilla.redhat.com/show_bug.cgi?id=2440300 exploit

access.redhat.com/errata/RHSA-2026:3925 (RHSA-2026:3925) vendor-advisory

access.redhat.com/errata/RHSA-2026:3926 (RHSA-2026:3926) vendor-advisory

access.redhat.com/errata/RHSA-2026:3947 (RHSA-2026:3947) vendor-advisory

access.redhat.com/errata/RHSA-2026:3948 (RHSA-2026:3948) vendor-advisory

access.redhat.com/security/cve/CVE-2026-2603 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2440300 (RHBZ#2440300) issue-tracking

cve.org (CVE-2026-2603)

nvd.nist.gov (CVE-2026-2603)

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