CVE Catalog

CVE-2026-62863

CriticalCVSS 9.6
Published: Translated: NVD NIST

Summary

MoLing in SSE mode (started with -l) does not authenticate requests to the /sse and /message endpoints, and the mcp-go dependency sets Access-Control-Allow-Origin: *. A malicious web page can open a cross-origin EventSource to /sse, read the sessionId, and send unauthorized MCP tool calls via /message, potentially leading to file read/write or command execution. The issue is fixed in version 0.5.0.

Risk Assessment

An attacker can take control of the victim's MCP tools after the victim visits a malicious page, even if the service listens only on loopback. This can result in unauthorized file access, command execution, and other actions in the server context.

Recommendation

Update MoLing to version 0.5.0 or later. Until then, avoid running SSE mode with the -l option in environments where a browser can reach the service.

Related vulnerabilities

Original NVD description (English source)

MoLing is a computer-use and browser-use based MCP server. Prior to 0.5.0, when MoLing runs in SSE mode using `-l`, its `/sse` and `/message` HTTP endpoints do not authenticate requests and the `mcp-go` dependency sets `Access-Control-Allow-Origin: *`. A malicious web page can open a cross-origin `EventSource` to `/sse`, including a loopback listener, and read the `endpoint` event to obtain `sessionId`. After a victim running SSE mode visits that page, the attacker can use the disclosed `sessionId` against `/message` to send unauthorized MCP tool calls. Depending on the configured tools, those calls can read or write local files, execute commands or perform other actions. Binding only to loopback does not prevent this browser-mediated attack. This issue is fixed in version 0.5.0.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS