CVE-2026-23904 in Kyuubi
Summary
by MITRE • 07/29/2026
Kyuubi Engine UI proxy accepts a host and port from the request path and proxies HTTP requests to that destination. A remote requester with network access to the proxy can cause the Kyuubi server to send HTTP requests to arbitrary reachable hosts, resulting in SSRF or open-proxy behavior.
This issue affects Apache Kyuubi: from 1.8.0 before 1.12.0.
Users are recommended to upgrade to version 1.12.0, which disables the proxy by default. To restore proxied Engine UI, set kyuubi.frontend.rest.engine.ui.proxy.enabled=true and configure allowed target hosts with kyuubi.frontend.rest.engine.ui.proxy.hosts.
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Analysis
by VulDB Data Team • 07/29/2026
The vulnerability in question represents a critical server-side request forgery flaw within the Apache Kyuubi Engine UI proxy functionality. This security weakness allows remote attackers with network access to the proxy service to manipulate the proxy behavior by supplying arbitrary host and port parameters through the request path. The affected versions span from 1.8.0 through 1.11.x, creating a substantial attack surface where malicious actors could potentially exploit this vulnerability to gain unauthorized access to internal systems or services that would otherwise be protected by network segmentation.
The technical implementation of this flaw stems from insufficient input validation and sanitization within the proxy component that processes user-supplied parameters in the HTTP request path. When the Kyuubi server receives a request containing host and port information, it directly forwards HTTP requests to the specified destination without proper authorization checks or destination validation. This behavior creates an open proxy scenario where the server becomes an unwitting conduit for traffic originating from external sources, potentially enabling attackers to bypass network security controls and access internal resources that should remain protected.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable various attack vectors including internal network reconnaissance, service enumeration, and potential lateral movement within compromised environments. Attackers could leverage this flaw to probe internal systems, attempt credential spraying against internal services, or even establish command and control channels through the proxy. The open-proxy nature of this vulnerability means that any network-accessible host on the same network segment as the Kyuubi server could become a target for malicious traffic originating from the compromised proxy.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-918 Server-Side Request Forgery and aligns with ATT&CK technique T1071.004 Application Layer Protocol: DNS, where attackers can abuse legitimate proxy functionality to bypass network controls. The issue demonstrates poor input validation practices that violate fundamental security principles outlined in secure coding standards. Organizations utilizing affected Kyuubi versions face significant risk of unauthorized internal system access and potential data exfiltration through this proxy mechanism.
The recommended mitigation strategy involves upgrading to version 1.12.0 or later, which addresses the vulnerability by disabling the proxy functionality by default. This approach follows the principle of least privilege, ensuring that the proxy feature is not enabled unless explicitly required for legitimate business purposes. When organizations need to restore the proxied Engine UI functionality, they must explicitly enable the feature through configuration parameters and define a whitelist of allowed target hosts. This configuration-based approach aligns with security best practices for implementing controlled access controls and prevents the open-proxy behavior that makes this vulnerability exploitable. The mitigation strategy emphasizes defense in depth by requiring explicit configuration changes to activate potentially dangerous functionality, reducing the likelihood of accidental exposure in production environments.