CVE-2026-108334 in Connectivity Link 1
Summary
by MITRE • 10/15/2026
A flaw was found in the internal WebAssembly (WASM) shim used by the Kuadrant operator. When generating the CEL predicate that determines whether Gateway-level authentication and rate limiting should run, the shim does not correctly escape values from HTTPRoute match fields. A user who can create or modify an HTTPRoute attached to a shared Gateway can provide a crafted path, header, or query match value that causes the predicate to skip those checks. The request is still forwarded to the route’s backend.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in the Kuadrant operator stems from a critical input validation failure within its internal WebAssembly shim, which serves as the execution environment for Common Expression Language predicates used by Envoy sidecars. These predicates are responsible for evaluating whether specific security policies, such as Gateway-level authentication and rate limiting, should be enforced on incoming traffic routed through an HTTPRoute resource. The core technical flaw lies in the improper escaping of values extracted from HTTPRoute match fields before they are interpolated into the CEL predicate logic. This lack of sanitization allows a malicious actor who possesses permissions to create or modify an HTTPRoute attached to a shared Gateway to inject crafted payloads directly into path, header, or query parameters defined within the route's matching rules.
When these unescaped values are processed by the WebAssembly shim, they alter the logical structure of the generated CEL predicate in unintended ways. Specifically, the injection can cause the evaluation logic to bypass security checks entirely for requests that match the crafted criteria. For instance, an attacker might craft a path or header value that terminates the conditional check prematurely or evaluates to true regardless of actual authentication status. As a result, traffic matching these specific patterns is forwarded directly to the backend service without undergoing the intended authentication verification or rate limiting controls. This effectively creates a security policy bypass mechanism where authorized users can exploit route configuration privileges to circumvent gateway-level protections designed to protect downstream services from unauthorized access and abuse.
The operational impact of this vulnerability is significant, particularly in multi-tenant environments where shared Gateways are used to manage traffic for multiple applications or teams. An attacker with write access to HTTPRoute resources could bypass authentication mechanisms, potentially gaining unauthorized access to backend APIs that require strict identity verification. Furthermore, the ability to evade rate limiting allows for denial-of-service attacks against specific endpoints by sending high volumes of requests that appear legitimate due to their crafted match fields. This undermines the integrity of the service mesh's security posture and violates the principle of least privilege, as route configuration permissions are being leveraged to escalate access rights beyond what is intended by the system administrators who configured the gateway policies.
From a classification perspective, this vulnerability aligns with CWE-79, which covers Improper Neutralization of Input During Web Page Generation, specifically in the context of code generation and logic injection within server-side configurations. It also relates to CWE-613, Insufficient Session Expiration, if the bypass allows persistent unauthorized access, though it is more accurately described as a Logic Error leading to Authorization Bypass via CWE-287. In terms of adversary tactics, this exploit maps to MITRE ATT&CK technique T1548.001, Abuse Configuration: Default Configurations, or more precisely T1659, which involves leveraging misconfigured access controls and logic flaws in cloud-native environments. The attack vector is local within the context of Kubernetes API permissions rather than remote network exploitation, requiring initial compromise of route configuration rights.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. Operators should immediately upgrade to a patched version of Kuadrant that addresses the input escaping logic in the WebAssembly shim. In environments where upgrading is not immediately feasible, administrators can implement stricter Role-Based Access Control policies within Kubernetes to limit which users or service accounts are permitted to create or modify HTTPRoute resources attached to shared Gateways with sensitive security policies applied. Additionally, implementing network-level segmentation and ensuring that backend services enforce their own independent authentication checks provides a defense-in-depth layer that remains effective even if gateway-level controls are bypassed through this specific vulnerability vector. Regular auditing of route configurations for unexpected patterns can also help detect potential exploitation attempts in real-time.