no f***ing way

Quick Overview

A critical remote code execution (RCE) vulnerability, tracked as CVE-2026-20841, existed in Windows 11 Notepad because the application improperly sanitized special elements in Markdown links, allowing attackers to execute local or remote programs silently by tricking users into clicking a specially crafted link, which Microsoft has since fixed in the February 2026 Patch Tuesday updates.

Key Points: Microsoft fixed a high-severity Remote Code Execution (RCE) vulnerability in Windows 11 Notepad, tracked as CVE-2026-20841. The flaw was caused by improper neutralization of special elements used in a command injection within Markdown links displayed by Notepad. Attackers could trick users into clicking a malicious Markdown link that pointed to local executable files or special URIs (like ms-appinstaller:), causing code execution without security warnings. The exploit was demonstrated using a URI pointing to a remote SMB share containing a batch file, which executed upon clicking the link. The vulnerability stems from Notepad gaining network-aware rendering capabilities (like Markdown support) without properly sanitizing URI handling, contrasting with its long history as a simple text utility. The fix requires users to click the link, which now displays a 'This link may be unsafe' warning, preventing silent execution. The video sponsor, ThreatLocker, demonstrates how their Zero Trust endpoint protection platform detects and blocks the execution of the malicious script, even when the Windows built-in warning is bypassed.

Context: The video discusses a significant security flaw discovered in the updated version of Windows 11 Notepad, which gained Markdown support, allowing it to process links. This feature introduced a critical vulnerability where specially crafted Markdown links could be used to execute arbitrary code or files on a victim's system without triggering standard Windows security prompts, leading to a Remote Code Execution (RCE) scenario.

Detailed Analysis