Microsoft Patch Tuesday: 8 Critical Fixes to Prioritize Today

September 12, 2025
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Introduction — Patch Tuesday just landed. Now what?

Microsoft rolled out its September 9, 2025 security updates. More than 80 vulnerabilities were fixed, and some are critical. Admins now face the big question: what do we patch first?

This guide breaks it down. You’ll see which fixes matter most, who should patch first, and simple commands you can copy and run. The idea is to stay calm, patch quickly, and reduce risk in an organized way.

Quick triage rule — who fixes what, in order

Not all systems carry the same risk. A simple order helps:

  1. Internet-facing hosts first
  2. Domain controllers, file servers, Hyper-V hosts next
  3. Developer machines and build servers
  4. Remote workers last (but don’t delay too much)

Internet-facing systems are most exposed. Domain controllers and file servers protect your keys and data. Developer machines can spread compromise into pipelines. Remote users are many, but patching them after core systems keeps the highest risk under control.

The 8 critical fixes to prioritize now

Here are the eight high-impact patches. Each includes why it matters, risk, what to do, and a quick command snippet.

1) NTLM Elevation of Privilege (High)

Why care: Attackers can use NTLM flaws to escalate privileges. Domain controllers are prime targets.

Risk: High — actively exploitable.

Action: Patch domain controllers and authentication servers now. Turn on NTLM auditing temporarily.


Get-HotFix | Where-Object {$_.Description -match "Security Update"}
auditpol /set /subcategory:"NTLM Authentication" /success:enable /failure:enabl

2) SMB Elevation of Privilege (High, Publicly Disclosed)

Why care: SMB flaws often lead to relay or escalation attacks. Public disclosure raises the urgency.

Risk: High.

Action: Patch SMB servers fast. If patching takes time, block external SMB access on firewalls.


Get-SmbServerConfiguration | Select EnableSecuritySignature, RequireSecuritySignature
Set-SmbServerConfiguration -EnableSecuritySignature $true -RequireSecuritySignature $true
Get-NetTCPConnection -LocalPort 445 -State Listen

3) Office Remote Code Execution (Critical)

Why care: Malicious Office docs can run code when opened. A classic phishing vector.

Risk: High.

Action: Patch Office clients and servers. Disable automatic preview if possible.


Install-Module PSWindowsUpdate -Force
Get-WindowsUpdate -AcceptAll
Install-WindowsUpdate -AcceptAll -AutoReboot

4) NTFS Remote Code Execution (Critical)

Why care: NTFS parsing flaws allow code execution via file shares or virtual desktops.

Risk: High.

Action: Patch file servers and VDI hosts. Isolate older unpatched systems.


Get-ADComputer -Filter {OperatingSystem -Like "*Server*"} -Properties Name | Select Name
Invoke-Command -ComputerName FileServer01 -ScriptBlock { Install-WindowsUpdate -AcceptAll -AutoReboot }

5) Hyper-V Remote Code Execution (Critical)

Why care: A guest escape can compromise the entire host. Many VMs are at risk.

Risk: High.

Action: Patch Hyper-V hosts and pause migrations until patched.


Get-VMHost
Invoke-Command -ComputerName HyperVHost01 -ScriptBlock { Install-WindowsUpdate -AcceptAll -AutoReboot }

6) Graphics Stack RCEs (Medium–High)

Why care: Crafted media files can trigger flaws. Often need user interaction, but still risky.

Risk: Medium–High.

Action: Patch clients and servers that process images. Enable file scanning at gateways.

7) SharePoint and Office Web RCEs (Medium–High)

Why care: Collaboration servers are a common entry point.

Risk: Medium–High.

Action: Patch SharePoint and Office Web Apps. Disable risky preview features until patched.

8) Cloud Agent and Azure Networking Fixes (Medium)

Why care: Cloud agent flaws can create privilege or stability issues.

Risk: Medium.

Action: Patch cloud agents and rotate credentials if needed. Monitor cloud logs closely.


az vm run-command invoke -g MyRG -n MyVM --command-id RunShellScript --scripts "sudo apt update && sudo apt upgrade -y"

Role-based playbooks

For SMB IT (small offices)

  1. Patch internet-facing hosts, file servers, and domain controllers first.
  2. Push client updates with Group Policy or simple scripts.

UsoClient StartScan
UsoClient StartInstall
Install-Module PSWindowsUpdate -Force
Install-WindowsUpdate -AcceptAll -AutoReboot

For Dev teams

  1. Patch build agents, CI runners, and artifact stores.
  2. Rebuild base images and test pipelines.

sudo apt update && sudo apt upgrade -y
sudo yum update -y

For Remote workers

  1. Send simple update instructions via email.
  2. Use Intune or similar tools for enforcement.

User step to share: Settings → Windows Update → Check for updates → Restart.

If a patch breaks things

  1. Pause rollout.
  2. Restore from snapshot or rollback.
  3. Open vendor ticket if needed.
  4. Always reboot after updates.

Monitoring and verification

Check updates:


Get-HotFix | Sort-Object InstalledOn -Descending | Select HotFixID, InstalledOn

Run scanners or management tools to confirm patches applied.

Additional safeguards while you patch

  1. Block unused services (SMB/RDP) at the firewall.
  2. Enforce MFA for remote access.
  3. Limit admin accounts and check for new accounts daily.
  4. Boost monitoring on domain controllers.
  5. Keep backups and snapshots ready.

Final note

Patch Tuesday can feel overwhelming, but it’s manageable with order. Focus on internet-facing systems and domain controllers first, then work down the list. Keep users informed and don’t skip the reboot.

You don’t need to fix everything in one night — but you must start with the riskiest systems. Clear priorities, small steady steps, and good communication will keep your environment safe.

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