Summary
MCP Inspector is Vulnerable to Potential Command Execution via XSS When Connecting to an Untrusted MCP Server
An XSS flaw exists in the MCP Inspector local development tool when it renders a redirect URL returned by a remote MCP server. If the Inspector connects to an untrusted server, a crafted redirect can inject script into the Inspector context and, via the built-in proxy, be leveraged to trigger arbitrary command execution on the developer machine. Version 0.16.6 hardens URL handling/validation and prevents script execution.
Thank you to the following researchers for their reports and contributions:
- Raymond (Veria Labs)
- Gavin Zhong, [email protected] & Shuyang Wang, [email protected].
Impact
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-58444? CVE-2025-58444 is a high-severity cross-site scripting (XSS) vulnerability in @modelcontextprotocol/inspector (npm), affecting versions < 0.16.6. It is fixed in 0.16.6. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of @modelcontextprotocol/inspector are affected by CVE-2025-58444? @modelcontextprotocol/inspector (npm) versions < 0.16.6 is affected.
- Is there a fix for CVE-2025-58444? Yes. CVE-2025-58444 is fixed in 0.16.6. Upgrade to this version or later.
- Is CVE-2025-58444 exploitable, and should I be worried? Whether CVE-2025-58444 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
- What actually determines whether CVE-2025-58444 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.
- How do I fix CVE-2025-58444? Upgrade
@modelcontextprotocol/inspectorto 0.16.6 or later.