How to fix CVE-2025-49596?

Within 24 hours: Identify all systems running MCP Inspector and their current versions; isolate affected instances from production networks if possible. Within 7 days: Upgrade all MCP Inspector installations to version 0.14.1 or later; verify upgrades are complete across development, testing, and staging environments. Within 30 days: Conduct security audit of affected systems for signs of compromise; review and rotate any credentials that may have been exposed; implement network access controls to restrict MCP Inspector usage.

CVE-2025-49596

EUVD-2025-20870 CRITICAL

2025-06-13 [email protected]

GHSA-7f8r-222p-6f5g

RCE Authentication Bypass

9.4

CVSS 4.0

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Lifecycle Timeline

Patch Released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 14, 2026 - 21:34 vuln.today

EUVD ID Assigned

Mar 14, 2026 - 21:34 euvd

EUVD-2025-20870

PoC Detected

Jul 09, 2025 - 21:15 vuln.today

Public exploit code

CVE Published

Jun 13, 2025 - 20:15 nvd

CRITICAL 9.4

DescriptionNVD

The MCP inspector is a developer tool for testing and debugging MCP servers. Versions of MCP Inspector below 0.14.1 are vulnerable to remote code execution due to lack of authentication between the Inspector client and proxy, allowing unauthenticated requests to launch MCP commands over stdio. Users should immediately upgrade to version 0.14.1 or later to address these vulnerabilities.

AnalysisAI

MCP Inspector versions below 0.14.1 contain a critical authentication bypass vulnerability (CVE-2025-49596) that enables unauthenticated remote code execution through unprotected communication between the Inspector client and proxy. Attackers can exploit this over the network without user interaction beyond the initial proxy connection to execute arbitrary MCP commands via stdio, achieving complete system compromise with CVSS 9.4 severity. The vulnerability requires immediate patching as it represents a complete authentication failure in a developer tool that is typically deployed on development systems with elevated privileges.

Technical ContextAI

MCP Inspector is a debugging tool for Model Context Protocol (MCP) servers that facilitates communication between clients and MCP servers via proxy mechanisms. The vulnerability stems from CWE-306 (Missing Authentication Check), where the proxy component fails to implement any authentication mechanism to verify that incoming requests are legitimate. The Inspector uses stdio-based command execution to interact with MCP servers, and without authentication checks, an unauthenticated attacker can craft and send malicious requests directly to the proxy endpoint. The root cause is the absence of security token validation, cryptographic verification, or any form of access control between the client interface and the proxy server. This is a design-level flaw rather than an implementation bug, as no authentication framework was integrated into the proxy communication layer.

RemediationAI

IMMEDIATE ACTION: Upgrade MCP Inspector to version 0.14.1 or later. Installation steps vary by platform: (1) npm users: npm install -g mcp-inspector@latest or npm update mcp-inspector, (2) pip users: pip install --upgrade mcp-inspector, (3) Verify upgrade: mcp-inspector --version should report >= 0.14.1. SHORT-TERM MITIGATION (if immediate upgrade is blocked): Restrict network access to the MCP Inspector proxy using host-based firewalls (iptables, Windows Firewall) to only trusted hosts; ensure the proxy binds to 127.0.0.1 (localhost only) rather than 0.0.0.0; disable MCP Inspector when not actively developing; if the proxy must be network-accessible, place it behind an authentication-enabled reverse proxy (nginx with auth_request, Apache with mod_auth) until patching. LONG-TERM: Subscribe to Anthropic security advisories and enable automatic updates for development tools to prevent similar issues.

CVE-2025-49596 vulnerability details – vuln.today

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