CVE-2025-49596: MCP Inspector RCE from the browser (< 0.14.1)

What happened

• According to GitHub Advisory Database's advisory (June 13, 2025), MCP Inspector, a developer tool for testing MCP servers, had no authentication between the Inspector client and its proxy, so unauthenticated requests could launch MCP commands over stdio. [1]
• Oligo showed it could be chained with the "0.0.0.0-day" browser flaw to take over a developer's machine through the browser, without being on the same network. [2]

Impact

• Remote code execution on the developer's machine; rated Critical with CVSS 9.4. [2]

What was done

• Anthropic fixed it in MCP Inspector 0.14.1. [1][2]

How to protect yourself

• Upgrade MCP Inspector to 0.14.1 or later. [1]

Sources

1. GHSA-7f8r-222p-6f5g — GitHub Advisory Database
2. Critical RCE in Anthropic MCP Inspector (CVE-2025-49596) — Oligo Security

Every statement above was checked against these sources before publishing. Spotted an error? Tell us and we will correct it with a dated note.