CVE-2026-2092 in Keycloak
Summary
by MITRE • 03/18/2026
A flaw was found in Keycloak. Keycloak's Security Assertion Markup Language (SAML) broker endpoint does not properly validate encrypted assertions when the overall SAML response is not signed. An attacker with a valid signed SAML assertion can exploit this by crafting a malicious SAML response. This allows the attacker to inject an encrypted assertion for an arbitrary principal, leading to unauthorized access and potential information disclosure.
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Analysis
by VulDB Data Team • 03/22/2026
The vulnerability identified as CVE-2026-2092 represents a critical security flaw within the Keycloak identity management platform that specifically affects the Security Assertion Markup Language SAML broker endpoint implementation. This issue stems from improper validation mechanisms that fail to adequately verify encrypted assertions when the broader SAML response lacks a signature. The flaw exists within Keycloak's SAML processing logic where the system assumes that if a SAML response contains a valid signature, then all contained assertions must also be trustworthy, regardless of their encryption status. This logical gap creates a significant attack surface that adversaries can exploit to manipulate authentication flows and gain unauthorized access to protected systems.
The technical exploitation of this vulnerability occurs through a sophisticated attack vector where an attacker with access to a valid signed SAML assertion can craft malicious SAML responses that contain encrypted assertions for arbitrary principals. The flaw operates at the intersection of SAML protocol security mechanisms and Keycloak's trust model, specifically targeting the validation sequence where encrypted assertions are processed without proper verification of their integrity when the containing response lacks a signature. This vulnerability directly maps to CWE-295, which addresses improper certificate validation, and CWE-347, which covers improper verification of cryptographic signatures, as the system fails to validate the cryptographic integrity of encrypted elements within unsigned SAML responses. The attack leverages the trust relationship established between SAML providers and consumers, where the system incorrectly assumes that encrypted content within a signed response maintains its security properties even when the response itself is not cryptographically verified.
The operational impact of CVE-2026-2092 extends beyond simple unauthorized access to encompass potential information disclosure and privilege escalation within systems relying on Keycloak for SAML-based authentication. Organizations using Keycloak as a SAML identity provider or broker face significant risk of unauthorized user impersonation, where attackers can inject encrypted assertions that appear legitimate to the system. This vulnerability particularly affects environments where SAML responses may be processed without strict signature verification, which is common in federated identity scenarios where trust relationships are established through certificate-based authentication. The attack can lead to complete compromise of authentication flows, potentially allowing attackers to gain access to sensitive applications, data, and system resources that would otherwise require legitimate authentication credentials.
Organizations should implement immediate mitigations including enforcing strict signature validation for all SAML responses regardless of encryption status, implementing additional assertion validation checks, and monitoring for suspicious SAML response patterns. The recommended approach involves configuring Keycloak to require signature validation for all SAML responses before processing any encrypted assertions, thereby eliminating the attack vector that exploits the trust relationship between signed responses and encrypted content. Security teams should also consider implementing automated monitoring solutions that can detect anomalous SAML response structures and validate cryptographic integrity before any assertion processing occurs. According to ATT&CK framework, this vulnerability aligns with T1566.002 which covers phishing via service providers, and T1078.004 which addresses valid accounts through compromised credentials, as attackers can effectively impersonate legitimate users through crafted SAML assertions. The mitigation strategy should include comprehensive testing of SAML configurations, regular security assessments of identity federation implementations, and implementation of principle of least privilege controls to limit the potential impact of successful exploitation.