EUVD-2026-51479
GHSA-82v3-6227-jc8x
Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Network vector with no attacker privileges; high complexity due to required wildcard redirect config; scope changed to SP; integrity-only impact.
Primary rating from Vendor (redhat).
CVSS VectorNVD
Lifecycle Timeline
4DescriptionNVD
A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, an attacker can craft a request that includes malicious parameters. When a user authenticates, Keycloak appends its legitimate response to the attacker's parameters. This can cause some service providers to process the attacker's data instead of the real login information, potentially leading to a user being logged into the wrong account.
AnalysisAI
SAML HTTP-Redirect binding in Keycloak allows network-based attackers to inject malicious parameters into authentication requests targeting clients configured with wildcard redirect URLs. When a victim user completes authentication, Keycloak appends its legitimate SAML response to the attacker-controlled URL parameters, which can cause susceptible service providers to process the attacker's data instead of the real login assertion - potentially resulting in the victim being logged into the wrong account. No public exploit is identified at time of analysis, and the CVSS score of 3.4 (Low) reflects the high attack complexity and limited integrity-only impact.
Technical ContextAI
Keycloak's SAML HTTP-Redirect binding encodes authentication requests and responses as URL query parameters rather than POST body content, making them susceptible to parameter injection when redirect URL validation is insufficiently strict. The root cause is CWE-20 (Improper Input Validation): Keycloak does not adequately validate or sanitize attacker-supplied parameters present in the SAML redirect URL before appending its own legitimate response, allowing parameter confusion at the service provider. The affected products per CPE data include Red Hat Build of Keycloak (multiple versions), Red Hat Data Grid 8, Red Hat JBoss Enterprise Application Platform Expansion Pack, and Red Hat Single Sign-On 7. The attack is specifically contingent on clients being configured with wildcard redirect URLs, which is a non-default but not uncommon configuration in multi-tenant or multi-environment deployments.
RemediationAI
No specific patched version is confirmed from the available input data. Organizations should consult the Red Hat security advisory at https://access.redhat.com/security/cve/CVE-2026-18217 and Bugzilla entry https://bugzilla.redhat.com/show_bug.cgi?id=2508311 for patch availability and exact fix versions as they become available. As a targeted compensating control, administrators should audit all SAML client configurations in Keycloak and replace wildcard redirect URLs with exact, fully-qualified redirect URIs - this directly eliminates the configuration precondition required for exploitation and has no meaningful functional trade-off for production deployments with known redirect targets. Additionally, restricting SAML HTTP-Redirect binding in favor of HTTP-POST binding (where parameters are not URL-encoded and therefore not subject to this injection vector) is an effective architectural mitigation, though it requires coordinated changes with service providers and may not be feasible for all integrations.
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Same weakness CWE-20 – Improper Input Validation
View allSame technique Information Disclosure
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