CVE-2026-62863CWE-306CWE-942

MoLing: unauthenticated SSE and wildcard CORS expose tool sessions

Critical · published October 30, 2026

CVSS v3.1
9.6
EPSS
—
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.6 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
CVSS v4.0
Not supplied
EPSS
Not scored
Weaknesses
CWE-306 · Missing Authentication for Critical Function; CWE-942 · Permissive Cross-domain Security Policy with Untrusted Domains
Published
2026-10-30T20:33Z
Timeline
  • 30 OCT 20:33Z
    MoLing: unauthenticated SSE and wildcard CORS expose tool sessions
    cvelistv5
  • 30 OCT 20:33Z
    MoLing: unauthenticated SSE and wildcard CORS expose tool sessions
    cvelistv5