Micropatches released for Windows Active Directory Domain Services Remote Code Execution Vulnerability (CVE-2026-49179)

Mitja KolsekOct 22, 2026
Micropatches released for Windows Active Directory Domain Services Remote Code Execution Vulnerability (CVE-2026-49179)

August 2026 Windows Updates brought a patch for CVE-2026-49179, a remote code execution vulnerability in Active Directory Domain Services. The vulnerability allowed a low-privileged attacker in the Windows domain to inject malicious code into a script that could subsequently be executed by administrator.

The vulnerability was found internally by Microsoft. Subsequently, Ryan Yager published their own analysis and proof of concept, which allowed us to reproduce the issue and create patches for legacy Windows systems.

The Vulnerability 

This is a command injection issue in Active Directory Lightweight Directory Services, a mode of Active Directory that provides directory services for applications. A remote attacker on another computer in the domain can send a malicious request to this service and cause it to generate a local helper BAT script containing an attacker-provided string without proper sanitization. This script is supposed to be executed by an admin for certain configuration purposes, and the vulnerability makes it possible for the attacker to escape quotes in the script and inject their own command.

Microsoft's Patch

Microsoft fixed this issue by completely changing the script-generating code, such that a patched service now generates a PowerShell (PS1) script instead of a batch(BAT) script.

We noticed that, while the patched code is no longer susceptible to the original exploit (which generated a malicious BAT script), it has its own similar flaw and a modified exploit can still produce the same effect - a malicious PS1 script. We have reported this to Microsoft and will not publish details until they have corrected their patch.

Our Patch

Instead of following Microsoft's patching direction, we decided to harden the existing BAT script-generating code to prevent command injection.

Micropatch Availability

Micropatches were written for the following security-adopted Windows versions:

  1. Windows 11 v22H2 - fully updated

  2. Windows 11 v21H2 - fully updated

  3. Windows 10 v22H2 - fully updated with no ESU

  4. Windows 10 v21H2 - fully updated

  5. Windows 10 v21H1 - fully updated

  6. Windows 10 v20H2 - fully updated

  7. Windows 10 v2004 - fully updated

  8. Windows 10 v1909 - fully updated

  9. Windows 10 v1809 - fully updated

  10. Windows 10 v1803 - fully updated

  11. Windows Server 2008 R2 - fully updated with no ESU, with ESU 1, ESU 2, ESU 3 or ESU 4

  12. Windows Server 2012 - fully updated with no ESU, with ESU 1

  13. Windows Server 2012 R2 - fully updated with no ESU, with ESU 1

 

Micropatches have already been distributed to, and applied on, all affected online computers with 0patch Agent in PRO or Enterprise accounts (unless Enterprise group settings prevented that).

Vulnerabilities like these get discovered on a regular basis, and attackers know about them all. If you're using Windows that aren't receiving official security updates anymore, 0patch will make sure these vulnerabilities won't be exploited on your computers - and you won't even have to know or care about these things. 

We'd like to thank Ryan Yager for sharing their proof-of-concept, which allowed us to create patches for Windows versions that are no longer receiving official updates from Microsoft.

If you're new to 0patch, create a free account in 0patch Central, start a free trial, then install and register 0patch Agent. Everything else will happen automatically. No computer reboot will be needed.

Did you know 0patch security-adopted Windows 10 and Office 2016 and 2019 when they went out of support in October 2025, allowing you to keep using them for at least 3 more years (5 years for Windows 10)? Read more about it here and here. 

Note that we have recently also security-adopted the following products:

  1. Windows 10 22H2 with Extended Security Updates year 1: October 2026

  2. Windows Server 2012 with Extended Security Updates year 3: October 2026

  3. Windows Server 2012 R2 with Extended Security Updates year 3: October 2026

  4. Microsoft Office 2021: October 2026

And will soon adopt additional ones:

  1. Windows 11 23H2 (E): November 2026

  2. Windows Server 2016: January 2027

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