CVE-2026-62863: Missing Auth (CVSS 9.6)

Description

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.

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CVSS v3.1 Score

9.6

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

Weakness Type (CWE)

CWE-306 Missing Authentication

CWE-942 CWE-942

References

Other References

https://github.com/gojue/moling/commit/ae07f704cbc88d4419fc0fbaec278090fcd0502d https://github.com/gojue/moling/pull/48 https://github.com/gojue/moling/releases/tag/v0.5.0 https://github.com/gojue/moling/security/advisories/GHSA-qpgh-hp5g-4vwp

Frequently Asked Questions

What is CVE-2026-62863? +

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. It has a CVSS v3.1 base score of 9.6 (CRITICAL).

How severe is CVE-2026-62863? +

CVE-2026-62863 has a CVSS v3.1 score of 9.6 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

How do I check if I'm vulnerable to CVE-2026-62863? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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