---
id: "CVE-2026-123139"
page: "https://infrastack.ai/live/CVE-2026-123139"
kind: "vulnerability"
aliases: ["CVE-2026-123139"]
title: "Opera Neon: malicious browser extension can take control via MCP Hub"
severity: "medium"
cvss: 5.8
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["browser", "macos", "mcp", "opera-neon", "other", "windows"]
not_affected_if: ["no-malicious-extension-installed"]
published_at: "2026-11-12T13:17:11+00:00"
first_seen_at: "2026-11-12T13:38:24+00:00"
updated_at: "2026-11-12T13:38:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123139", "first_seen_at": "2026-11-12T13:38:24+00:00"}]
exploit_sources: []
---

# Opera Neon: malicious browser extension can take control via MCP Hub

Link for people: https://infrastack.ai/live/CVE-2026-123139 (this .md is for agents)

Opera Neon on macOS and Windows does not verify the source of commands sent through its MCP Hub extension to the built-in Browser Operator extension. A malicious browser extension can use this to send commands and take control of the browser.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-11-12T13:38:24+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123139

## From the sources

Improper verification of the source of a communication channel vulnerability in Opera Neon on macOS and Windows allows a malicious browser extension to take control of the browser by sending commands through MCP Hub to the built-in Browser Operator extension. This issue affects Opera Neon MCP Hub extension: 0.0.1.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_