Vulnerability · Published Mar 18, 2026 · Assigned by redhat
CVE-2026-2603Keycloak: keycloak: unauthorized authentication via disabled saml identity provider
High 8.1
In plain English
A high-severity missing authentication in Red Hat build of Keycloak 26.2 from Red Hat. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Maven | org.keycloak:keycloak-server-spi-private | 26.5.5 | GHSA-x4p7-7chp-64hq |
| Maven | org.keycloak:keycloak-services | 26.5.5 | GHSA-x4p7-7chp-64hq |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat build of Keycloak 26.2 | see references |
| Red Hat | Red Hat build of Keycloak 26.2 | see references |
| Red Hat | Red Hat build of Keycloak 26.2 | see references |
| Red Hat | Red Hat build of Keycloak 26.2.14 | see references |
| Red Hat | Red Hat build of Keycloak 26.4 | see references |
| Red Hat | Red Hat build of Keycloak 26.4 | see references |
| Red Hat | Red Hat build of Keycloak 26.4 | see references |
| Red Hat | Red Hat build of Keycloak 26.4.10 | see references |
Weakness: CWE-306 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
References
- RHSA-2026:3925 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:3926 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:3947 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:3948 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-2603 vdb-entry, x_refsource_REDHAT
- RHBZ#2440300 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2603.json x_sadp-csaf-vex