CVE-2026-42856: Network-AI Auth Bypass Vulnerability

CVE-2026-42856 Overview

CVE-2026-42856 is a missing authentication vulnerability [CWE-306] in Network-AI, a TypeScript/Node.js multi-agent orchestrator. The Model Context Protocol (MCP) HTTP transport accepts JSON-RPC tools/call requests without any authentication, session validation, origin check, or token verification. Requests are dispatched directly to the orchestrator's tool registry. The default bind address is 0.0.0.0, exposing the service to all reachable networks. Any attacker with network access can enumerate and invoke privileged management tools. The issue affects Network-AI prior to version 5.1.3 and is fixed in 5.1.3.

Critical Impact
Unauthenticated remote attackers can invoke privileged orchestrator tools over the network, leading to integrity loss across managed agents.

Affected Products

Network-AI multi-agent orchestrator versions prior to 5.1.3
Deployments exposing the MCP HTTP transport on the default 0.0.0.0 bind address
Any environment where the MCP endpoint is reachable from untrusted networks

Discovery Timeline

2026-05-11 - CVE-2026-42856 published to NVD
2026-05-13 - Last updated in NVD database

Technical Details for CVE-2026-42856

Vulnerability Analysis

Network-AI exposes a JSON-RPC interface over HTTP to support the Model Context Protocol (MCP). The MCP transport handler processes tools/call requests and forwards them to the orchestrator's tool registry. The handler performs no authentication, no session lookup, no origin header validation, and no bearer token check.

An attacker who can reach the listener can issue a tools/list request to enumerate registered tools, then issue tools/call requests to invoke them. The orchestrator tool registry includes privileged management capabilities, so successful invocation alters orchestrator state and downstream agent behavior. The vulnerability impacts integrity directly. Confidentiality and availability are not the primary axes affected per the CVSS vector, which scores VI:H with VC:N and VA:N.

Root Cause

The root cause is missing authentication on a sensitive function [CWE-306]. The MCP HTTP transport was implemented without a guard layer that validates the caller before dispatch. The default bind address of 0.0.0.0 compounds the issue by exposing the listener on all interfaces, including public ones in cloud and container deployments.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker sends a crafted HTTP POST containing a JSON-RPC payload to the MCP endpoint. The orchestrator parses the payload, locates the tool by name, and executes it with full orchestrator privilege. Reachability is the only precondition. Refer to the GitHub Security Advisory for the maintainer's technical description.

Detection Methods for CVE-2026-42856

Indicators of Compromise

Inbound HTTP POST requests to the MCP transport endpoint containing JSON-RPC methods tools/list or tools/call from unexpected source addresses.
Orchestrator logs showing tool invocations without a corresponding authenticated session identifier.
Network-AI listener bound to 0.0.0.0 and accepting connections from outside the management network.

Detection Strategies

Inspect Network-AI process logs for tools/call dispatches lacking originating user or session context.
Correlate orchestrator tool execution events with upstream proxy or load balancer access logs to identify unauthenticated calls.
Hunt for outbound effects of privileged tool invocations, such as unexpected agent configuration changes or downstream API calls.

Monitoring Recommendations

Alert on any traffic to the MCP HTTP port from outside an allowlisted management CIDR.
Monitor running Network-AI instances for the deployed version string and flag installations below 5.1.3.
Track JSON-RPC method frequency and alert on enumeration patterns such as repeated tools/list calls.

How to Mitigate CVE-2026-42856

Immediate Actions Required

Upgrade Network-AI to version 5.1.3 or later, which adds authentication to the MCP HTTP transport.
Restrict the listener bind address from 0.0.0.0 to 127.0.0.1 or a trusted internal interface until the upgrade is applied.
Place the MCP endpoint behind a reverse proxy that enforces authentication, mutual TLS, or an IP allowlist.
Review orchestrator audit logs for unauthorized tools/call invocations since the service was deployed.

Patch Information

The maintainer fixed the vulnerability in Network-AI 5.1.3. The patch introduces authentication, session, origin, and token validation on the MCP HTTP transport before dispatch to the tool registry. See the GitHub Security Advisory GHSA-fj4g-2p96-q6m3 for release details.

Workarounds

Bind the MCP transport to localhost and tunnel administrative access through SSH or a VPN.
Apply network ACLs or host firewall rules to restrict access to the MCP port to known management hosts.
Front the endpoint with a proxy that requires a bearer token or mTLS client certificate before forwarding requests.

bash

# Example host firewall rule restricting MCP HTTP transport to a management subnet
iptables -A INPUT -p tcp --dport 8080 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP