CVE-2026-62863: Unauthenticated Access in MoLing MCP Server

MoLing is an MCP server for computer-use and browser-use. CVE-2026-62863 is a critical vulnerability in SSE mode operation (enabled with -l flag). The HTTP endpoints /sse and /message do not require authentication, and the mcp-go client configures wildcard CORS. A malicious web page, visited by the victim, can open a cross-origin EventSource connection to /sse, read the sessionId from events, and use it to send unauthorized MCP tool calls to the /message endpoint.

The severity is declared critical with CVSS 9.6. The impact is concrete: depending on configured tools, unauthorized calls can read or write local files, execute arbitrary commands, or perform other dangerous actions. Binding to localhost does not prevent this attack as it is mediated by the victim's browser. The vulnerability was published on NVD on 2026-10-30. The fix is available from version 0.5.0. Social media shows 3 mentions in the last 24 hours. No public exploits reported on GitHub.

Administrators must immediately update MoLing to version 0.5.0 or later. If immediate upgrade is not possible, disable SSE mode until patching. Identify all environments where SSE is active, especially in development and staging. Review access logs for the /sse and /message endpoints to detect suspicious activity. If sensitive, conduct forensic analysis to verify sessionId compromise and unauthorized access or command execution.