CVE-2026-19263: mcp-bridge-api Command Injection RCE Flaw

CVE-2026-19263 Overview

CVE-2026-19263 is a command injection vulnerability in INQUIRELAB mcp-bridge-api affecting commits up to b30a82aa1d1d1139e0de846c41c8aadee6e06114. The flaw resides in mcp-bridge.js within the Servers Endpoint component. An unauthenticated remote attacker can manipulate the command or args arguments to execute arbitrary operating system commands on the host running the bridge. Because the project uses a rolling release model, no discrete affected or fixed version numbers are published, and the pull request addressing the issue remains pending acceptance. The weakness is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component.

Critical Impact
Remote, unauthenticated attackers can inject operating system commands through the Servers Endpoint, resulting in confidentiality, integrity, and availability impact on the host system.

Affected Products

INQUIRELAB mcp-bridge-api (rolling release)
Commits up to b30a82aa1d1d1139e0de846c41c8aadee6e06114
The mcp-bridge.js file within the Servers Endpoint component

Discovery Timeline

2026-08-08 - CVE-2026-19263 published to NVD
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-19263

Vulnerability Analysis

The mcp-bridge-api project exposes a Servers Endpoint that spawns child processes based on user-supplied parameters. The command and args fields are passed to process-execution routines in mcp-bridge.js without adequate neutralization of shell metacharacters. An attacker sending a crafted HTTP request can append or substitute arbitrary commands, which the Node.js runtime then executes with the privileges of the bridge process.

The attack requires no authentication, no user interaction, and can be performed over the network. Because MCP (Model Context Protocol) bridges are typically used to broker requests between AI agents and backend tooling, exploitation can pivot from AI orchestration layers into host command execution.

Root Cause

The root cause is improper input neutralization when the Servers Endpoint forwards untrusted command and args values into process-creation primitives. The handler does not enforce an allowlist, escape shell metacharacters, or invoke process spawning in a way that bypasses shell interpretation. This maps directly to [CWE-74] injection semantics applied to operating system command construction.

Attack Vector

An attacker sends an HTTP request to the exposed Servers Endpoint containing malicious command or args payloads. Shell metacharacters such as ;, &&, |, or backticks embedded in these fields cause the underlying shell to execute attacker-supplied commands in addition to, or instead of, the intended binary. Successful exploitation returns command output through the bridge or enables out-of-band exfiltration.

Detailed reproduction notes are tracked in the GitHub Issue Tracker and the VulDB Vulnerability Detail entry. No verified public exploit code has been released at the time of publication.

Detection Methods for CVE-2026-19263

Indicators of Compromise

Unexpected child processes such as sh, bash, cmd.exe, or powershell.exe spawned by the Node.js process hosting mcp-bridge-api.
HTTP requests to the Servers Endpoint containing shell metacharacters (;, |, &&, `, $() in the command or args parameters.
Outbound network connections initiated by the bridge process to unfamiliar hosts shortly after inbound API traffic.

Detection Strategies

Inspect application logs for Servers Endpoint requests where command or args deviate from an expected allowlist of binaries.
Correlate process-creation telemetry with the parent process identifier of the mcp-bridge-api service to flag anomalous descendants.
Deploy web application firewall or reverse-proxy rules that reject requests containing shell metacharacter patterns in JSON body fields destined for the bridge.

Monitoring Recommendations

Enable verbose request logging on the mcp-bridge-api service, including full request bodies for the Servers Endpoint.
Forward Node.js process telemetry and host process-creation events to a centralized SIEM for correlation.
Alert on any interactive shell descendant of the bridge process, since legitimate operation should invoke a bounded set of predictable binaries.

How to Mitigate CVE-2026-19263

Immediate Actions Required

Restrict network exposure of the mcp-bridge-api Servers Endpoint to trusted internal networks and place it behind authenticated ingress.
Run the bridge under a dedicated, unprivileged user account and, where possible, inside a container with a read-only filesystem and no shell binaries.
Track the pending fix through the GitHub Issue Comment and apply it as soon as it is merged.

Patch Information

As of the NVD publication date, no accepted upstream patch has been merged. The maintainer's pull request addressing the injection awaits acceptance. Because the project follows a rolling release, operators should pin to a specific commit only after the fix is merged and validated. Refer to the GitHub Project Repository for the latest state.

Workarounds

Front the bridge with a reverse proxy that enforces an allowlist on command values and rejects any args element containing shell metacharacters.
Modify local deployments to invoke child processes with an array-form argument list and shell interpretation disabled (shell: false in Node.js child_process.spawn).
Apply mandatory access controls such as AppArmor, SELinux, or seccomp profiles to prevent the bridge process from executing binaries outside a defined allowlist.

bash

# Example reverse-proxy allowlist enforcement (nginx)
location /servers {
    if ($request_body ~* "[;&|`$()]") { return 400; }
    proxy_pass http://127.0.0.1:3000;
}