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CriticalVulnerabilityCVE-2026-62863updated 30 Oct 2026, 21:20 UTC

MoLing MCP server lets web pages control it without login

If you run MoLing's network mode and open a malicious website, that site can quietly send commands to MoLing on your computer, which may read or change your files or run programs. Anyone on the internet who lures you to the page can do this

Fixed in Version 0.5.0. · out Official source
SeverityCriticalCVSS 9.6 of 10
Being exploited?UnclearNo reports either way yet
Fix available?YesVersion 0.5.0. · since 30 Oct 2026
How sure is this?Official sourceBacked by an official source

How the attack works simplified

  1. 1Attacker builds pagePage hosts cross-origin EventSource script
  2. 2Victim visits pageBrowser opens connection to local /sse
  3. 3sessionId leakedEndpoint event read due to wildcard CORS
  4. 4Forged tool callsSent to /message with stolen sessionId
  5. 5Files and commandsDepends on tools configured
  6. ResultAttacker runs actions on victim machine

What happened

MoLing versions before 0.5.0 running in SSE mode (-l) expose /sse and /message HTTP endpoints without authentication and send Access-Control-Allow-Origin: * via the mcp-go dependency. A malicious page can read the sessionId from the /sse endpoint event and then send unauthorized MCP tool calls to /message, even when bound to loopback.

Why it is dangerous: Attackers can use the MCP tools to read or write local files, execute commands, or perform other actions, all triggered by a victim simply visiting a web page while MoLing is running. Anyone running MoLing in SSE mode on a workstation is at risk.

Are you affected?

You are affected if you run MoLing before version 0.5.0 in SSE mode using the -l flag, regardless of whether it listens only on localhost.

MoLing versions prior to 0.5.0 running in SSE mode (-l).

What to do

  1. Update MoLing to version 0.5.0 or later
  2. Stop running MoLing in SSE mode (-l) until updated
  3. Avoid browsing untrusted websites while MoLing SSE mode is running

Timeline

  1. 30 Oct 2026, 21:17 UTC
    Publicly disclosed
  2. 30 Oct 2026, 21:17 UTC
    Reported by NVD · NVD
  3. 30 Oct 2026, 21:20 UTC
    Picked up by Zero Radar

Sources 1 report, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-62863
CVSS
9.6 / 10
Disclosed
30 Oct 2026, 21:17 UTC
On Zero Radar
30 Oct 2026, 21:20 UTC (3 min after disclosure)
Last change
30 Oct 2026, 21:20 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

MoLing MCP server lets web pages control it without login · Zero Radar