CVE-2026-16326 in consul-mcp-server
Summary
by MITRE • 07/29/2026
In consul-mcp-server, versions 0.1.0 up to 0.1.3 did not properly isolate session state in stateless mode, which may allow one client's Consul authentication token to be used for subsequent requests from other clients. This vulnerability (CVE-2026-16326) is fixed in consul-mcp-server 0.1.4.
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Analysis
by VulDB Data Team • 07/29/2026
The vulnerability identified as CVE-2026-16326 affects the consul-mcp-server component within versions 0.1.0 through 0.1.3, representing a critical session isolation flaw that undermines the security model of the application. This issue manifests in stateless mode operation where proper separation between client sessions is compromised, creating an environment where authentication tokens can be misused across different clients. The flaw directly impacts the server's ability to maintain distinct session contexts, potentially allowing unauthorized access to resources and data that should remain isolated between separate users or applications.
The technical root cause of this vulnerability lies in the improper handling of session state management within the server's stateless operation mode. When consul-mcp-server operates in stateless mode, it is designed to function without maintaining persistent session information on the server side. However, the implementation fails to properly isolate authentication contexts between concurrent clients, resulting in a cross-client token leakage scenario. This misconfiguration creates a path where one client's valid Consul authentication token can be inadvertently consumed by another client making subsequent requests, effectively enabling privilege escalation and unauthorized access.
The operational impact of this vulnerability extends beyond simple authentication bypass scenarios, potentially allowing attackers to gain elevated privileges and access sensitive data within the Consul service mesh environment. An attacker who successfully exploits this vulnerability could access configuration data, service discovery information, and other resources that are typically protected by proper session isolation mechanisms. The implications are particularly severe in production environments where consul-mcp-server acts as a critical component for service communication and security enforcement, potentially compromising entire service meshes if exploited at scale.
This vulnerability maps directly to CWE-285, which addresses improper authorization issues in software systems, and aligns with ATT&CK technique T1078.004 related to valid accounts and credential access. The flaw represents a classic case of insufficient session management where the server fails to properly validate and isolate client contexts, creating an attack surface that allows unauthorized token reuse. Organizations deploying consul-mcp-server in production environments should prioritize immediate remediation through updating to version 0.1.4, which implements proper session isolation mechanisms. Additional mitigations may include implementing network-level restrictions, monitoring for unusual authentication patterns, and conducting thorough security assessments of the service mesh environment.
The fix implemented in consul-mcp-server version 0.1.4 addresses the core session isolation issue by ensuring that each client's authentication token is properly scoped to their specific session context. This update enforces proper state separation between clients in stateless mode operation, preventing the cross-contamination of authentication tokens that previously enabled unauthorized access. Security teams should verify that the updated version correctly implements session isolation and monitor for any regression issues that might affect normal operational procedures while ensuring continued protection against this specific class of authorization bypass vulnerability.