CVE-2026-20841: Windows Notepad App Remote Code Execution Vulnerability

Overview

Severity
High (CVSS 7.8)
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Feb
Released
2026-02-10
Last Updated
2026-03-12
EPSS Score
0.14% (percentile: 34.9%)

Description

Improper neutralization of special elements used in a command ('command injection') in Windows Notepad App allows an unauthorized attacker to execute code locally.

FAQ

How could an attacker exploit this vulnerability? An attacker could trick a user into clicking a malicious link inside a Markdown file opened in Notepad, causing the application to launch unverified protocols that load and execute both remote and local files. According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution? The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. For example, when the score indicates that the Attack Vector is Local and User Interaction is Required, this could describe an exploit in which an attacker, through social engineering, convinces a victim to download and open a specially crafted file from a website which leads to a local attack on their computer.

Detection & Weaponization (1 sources)

Maturity: Exploit

  • GitHub PoC: 13 repositories

Affected Products (1)

Apps

  • Windows Notepad

Security Updates (1)

Acknowledgments

<a href="https://x.com/chen9918b">chen</a>, Kara Zaffarano, <a href="https://www.linkedin.com/in/diyarsaadi/">Diyar Saadi</a>, Tim Zheng, Rudolf &quot;divVerent&quot; Polzer with <a href="https://www.google.com/">Google LLC</a>, <a href="https://www.linkedin.com/in/diyarsaadi/">Diyar Saadi</a>, <a href="https://x.com/qymag1c">QYmag1c</a>, Matthew Selbrede, <a href="https://patyk.lol/">PatRyk</a>, <a href="https://www.linkedin.com/in/jad-ghamloush">Jad Ghamloush</a>, <a href="https://github.com/r888800009">lin.yx</a> with <a href="https://www.chtsecurity.com/">CHT Security Co., Ltd.</a>, <a href="https://www.linkedin.com/in/alasdair-gorniak/">Alasdair Gorniak</a> with <a href="https://delta.cyberm.ca/">Delta Obscura</a>, <a href="https://www.linkedin.com/in/cristian-papa-aa4a38212/">Cristian-Iulian Papa</a>, Anonymous

Revision History

  • 2026-02-10: Information published.
  • 2026-02-12: Added FAQ information. This is an informational change only.
  • 2026-02-12: Added an FAQ and updated the CVSS score. This is an informational change only.
  • 2026-03-12: To comprehensively address CVE-2026-20841, Microsoft has released February 2026 security updates for the Windows Notepad App. Microsoft recommends that customers install the update to be fully protected from the vulnerability.