External risk intelligence

MoLing SSE Mode Endpoint Disclosure and Unauthorized Tool Execution Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.6)

CVE-2026-62863

The vulnerability affects a local MCP server that is intended for developer use on a local machine. While the attack is browser-mediated, the target service is not designed to be an internet-facing application, edge service, or gateway. The required deployment pattern is local execution on a developer's workstation, which is typically isolated from public internet exposure.

Missing Authentication

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the MoLing MCP server could allow unauthorized actions if a user visits a malicious webpage, potentially leading to local file access, command execution, or other actions depending on configured tools.

Unauthenticated server endpoints can expose session IDs.
Sensitive tool calls could be executed without authorization.
Confirm relevance and determine system exposure.

Attack Path

How an attacker could exploit the issue

An attacker can trick a user into visiting a malicious webpage, which then opens a connection to a vulnerable MoLing server. This allows the attacker to steal a session identifier from the server's SSE endpoint. With this identifier, the attacker can send commands to the server through its message endpoint, potentially leading to unauthorized actions like file manipulation or command execution.

Requires user to visit a malicious website.
Leaks session ID via SSE endpoint.
Unauthorized tool calls and local actions.

Live Threat

Current exploitation, exposure, and threat context

When MoLing runs in SSE mode, unauthenticated HTTP endpoints could expose session IDs to malicious web pages. An attacker could then use these session IDs to send unauthorized commands to the server, potentially leading to the execution of arbitrary commands or local file manipulation, depending on the tools configured.

Server session IDs.
Malicious web page access.
Unauthorized tool execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

Real-world ownership likely resides with the development team responsible for the MoLing application, potentially in coordination with platform or infrastructure teams if MoLing is integrated into broader environments. The immediate practical step is to determine if MoLing is deployed and in SSE mode, and if so, assess its reachability and business criticality to prioritize remediation efforts.

Application developers own remediation.
Verify MoLing SSE mode and reachability.
Plan updates during maintenance windows.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is MoLing?

MoLing is a software tool that acts as a Model Context Protocol (MCP) server. It enables AI models or assistants to perform tasks by bridging them with your computer's browser and local system capabilities, allowing for automated actions like browsing or interacting with local files.

How does CVE-2026-62863 impact software security?

This vulnerability involves missing authentication and overly permissive cross-origin policies. Specifically, it falls under CWE-306 (Missing Authentication) and CWE-942 (Permissive Cross-domain Policy). Because the server fails to verify identity, an attacker's website can talk to your local MoLing instance, steal session credentials, and gain control over the tools MoLing is configured to run.

Can this be triggered if I bind the server to the local loopback address?

Yes. While developers often use loopback addresses to restrict access to the local machine, this specific vulnerability uses your web browser as a proxy. A malicious website you visit can initiate the attack from within your browser, bypassing the protection typically provided by a loopback-only configuration.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal indicates that this risk is very unlikely to affect critical production infrastructure. Because MoLing is designed as a local developer utility rather than an internet-facing gateway or edge service, its primary scope of impact is restricted to an individual developer's workstation environment.

What should I do if I use MoLing?

Check your current MoLing version immediately. If you are running a version prior to 0.5.0 in SSE mode, you should prioritize updating to version 0.5.0 or higher. This update includes the necessary security patches to ensure that your local endpoints are properly authenticated and protected against unauthorized access.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.