CVE-2026-16093: Reliance on Untrusted Inputs in a Security Decision in Red Hat Red Hat Build of Keycloak
Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.
AI Analysis
Technical Summary
The vulnerability in Red Hat Build of Keycloak involves a bypass of the Client Policies enforcement. Client Policies are intended to require clients to use signed JWTs for authentication. However, due to improper validation, an attacker possessing valid client credentials can supply a fake, unsigned assertion header. This tricks the system into believing the client has met the security requirements, allowing authentication with less secure methods such as client secrets. This undermines the intended security posture set by administrators.
Potential Impact
An attacker with valid client credentials can bypass enforced security policies requiring signed JWTs by submitting a fake unsigned assertion header. This reduces the authentication strength to simpler methods like client secrets, potentially allowing unauthorized access or privilege escalation within the affected Keycloak deployment. The impact is limited to confidentiality and integrity with no direct availability impact reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-16093 for current remediation guidance. Until an official fix is available, administrators should review client authentication policies and monitor for suspicious authentication attempts. No vendor advisory content currently states that no action is required or that the issue is already mitigated.
CVE-2026-16093: Reliance on Untrusted Inputs in a Security Decision in Red Hat Red Hat Build of Keycloak
Description
Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.
CVSS v3.1
Score 5.4medium
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Red Hat Build of Keycloak involves a bypass of the Client Policies enforcement. Client Policies are intended to require clients to use signed JWTs for authentication. However, due to improper validation, an attacker possessing valid client credentials can supply a fake, unsigned assertion header. This tricks the system into believing the client has met the security requirements, allowing authentication with less secure methods such as client secrets. This undermines the intended security posture set by administrators.
Potential Impact
An attacker with valid client credentials can bypass enforced security policies requiring signed JWTs by submitting a fake unsigned assertion header. This reduces the authentication strength to simpler methods like client secrets, potentially allowing unauthorized access or privilege escalation within the affected Keycloak deployment. The impact is limited to confidentiality and integrity with no direct availability impact reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-16093 for current remediation guidance. Until an official fix is available, administrators should review client authentication policies and monitor for suspicious authentication attempts. No vendor advisory content currently states that no action is required or that the issue is already mitigated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-07-17T14:08:34.722Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-16093","vendor":"Red Hat"}]
Threat ID: 6a5b5eba2d1edb114c7fb77f
Added to database: 07/18/2026, 11:08:42 UTC
Last enriched: 07/25/2026, 22:41:47 UTC
Last updated: 08/31/2026, 22:52:08 UTC
Views: 85
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