CVE-2026-62863: MoLing: unauthenticated SSE and wildcard CORS expose tool sessions

Published Oct 30, 2026

Updated

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.

Event History

Oct 30, 2026

CVE Published

via MITRE·08:33 PM

Data Sourced

via MITRE·08:33 PM

DescriptionSeverityWeakness

Data Sourced

via NVD·09:17 PM

DescriptionSeverityWeakness

Frequently Asked Questions

Who is exposed to this issue?

MoLing deployments running a version prior to 0.5.0 in SSE mode with the -l option are exposed. A loopback-only listener is still exposed because a victim's browser can connect to it from a malicious web page.

What does an attacker need to exploit it?

The attacker needs the victim to visit a malicious web page while the victim is running the affected MoLing SSE service. No authentication or prior privileges are required, and the page can obtain a sessionId from /sse and use it to issue requests to /message.

What is the likely impact after exploitation?

An attacker can send unauthorized MCP tool calls using the disclosed sessionId. The resulting impact depends on enabled tools and can include reading or writing local files, executing commands, or other tool-supported actions.

What should be done if patching cannot happen immediately?

The provided data identifies the affected condition as running SSE mode with -l. Avoid running MoLing in that mode until it can be updated to version 0.5.0, which fixes the issue.

CVE-2026-62863: MoLing: unauthenticated SSE and wildcard CORS expose tool sessions

Event History

Frequently Asked Questions

Who is exposed to this issue?

What does an attacker need to exploit it?

What is the likely impact after exploitation?

What should be done if patching cannot happen immediately?

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Frequently Asked Questions

Who is exposed to this issue?

What does an attacker need to exploit it?

What is the likely impact after exploitation?

What should be done if patching cannot happen immediately?