Microsoft at February 2026 Release security updates, fixes 58 vulnerabilities, which includes a rather eye-catching Windows Notepad High-risk remote code execution vulnerability (CVE-2026-20841). This vulnerability has a CVSS score of up to 8.8/10, belongs to the high-risk level. An attacker can take full control of a victim’s Windows system simply by convincing a user to open a Markdown file containing malicious content and click on the link.
CVE-2026-20841 Risk summary
- CVE number:CVE-2026-20841
- CVSS Rating:8.8/10(high risk)
- Vulnerability type:Remote Code Execution (RCE)
- Attack difficulty:Low (only the user clicks on the link)
- Scope of influence:Microsoft Store version of the modern Notepad app
Windows Notepad vulnerability principle and attack process
Root cause: Protocol handling flaw in Markdown functionality
New for Windows Notepad Markdown file support functionThere is a security flaw. Microsoft will add Markdown rendering functionality to Notepad in 2025, allowing users to directly process this lightweight markup language. However, security researchers have discovered that Notepad is unable to handle Markdown hyperlinksFailed to properly validate protocol handler. This lack of verification becomes an entry point for attackers to exploit.
Attack process analysis
Attackers exploiting this vulnerabilityComplete processas follows:
- Prepare malicious files: The attacker creates a malicious Markdown file (.md) containing a specially crafted link.
- Enticing users to open: Inducing victims into opening the file through phishing emails, instant messaging or other social engineering means
- User clicks link: When a user clicks the link in Notepad
- Starting an unauthenticated protocol handler: Notepad launches an unauthenticated protocol handler, loading and executing files from a remote server without proper authentication
- Gain control of the system: The attack is executed with user rights. If the victim has administrator rights, the hacker can completely take over the system.
The entire attack process does not require complex technical operations and only requires one click from the user. The threshold is extremely low but the harm is extremely high.
Impact Scope and Risk Assessment
| project | illustrate |
|---|---|
| Affected versions | Microsoft Store version of the modern Notepad app (Markdown-enabled version) |
| Not affected version | Old version of Notepad.exe (traditional Notepad program) |
| risk assessment | Since Notepad is a core component of Windows, nearly all modern Windows workstations are vulnerable to this vulnerability |
It is worth noting that this time February security updates patch a total of 58 vulnerabilities, including 6 that have been exploited by hackersZero-day vulnerabilities。
Fixes and user suggestions
Microsoft has February 10, 2026 This vulnerability is patched in a Windows cumulative update. Users should take the following measures:
Act now
- Automatic updates: Push updates to version through Microsoft Store 11.2510 or higher
- Manual check: Users can check Notepad updates through Microsoft Store
- Windows Update:Install the February 2026 Security Update
Security advice
- Avoid opening Markdown files (.md) from unknown sources
- Don’t click on untrustworthy links in Notepad
- Check for and install system updates regularly
- For high-risk users, consider temporarily using other text-only editors instead.
Source: KOCPC Chinese