Windows Defender update

It would be very unusual for Defender to not be updated since 2023 if you have Windows udpates enabled, usually the defender definitions are updated on a mostly daily basis.

1

Click your Start Button, type winver and hit Enter

Please provide a screenshot of the resulting dialog.

2

Please provide a screenshot of where you are seeing that Defender definitions are dated 2023.

To manually update Microsoft Defender Antivirus definitions on Windows 11 and fix outdated definitions:

1. Check the current definition version
   1. Open Start and search for Windows Security, then open it.
   2. Select Virus & threat protection.
   3. Under Virus & threat protection updates, select Protection updates or Virus & threat protection updates.
   4. Note the Security intelligence version and Last updated date.
2. Try updating from Windows Security
   1. In the same Virus & threat protection updates page, select Check for updates.
   2. Wait for the check and see if the Last updated date changes.
3. Manually install the latest security intelligence package
   1. Go to https://www.microsoft.com/wdsi/defenderupdates.
   2. Download the correct security intelligence update package for the system (x64 for most Windows 11 PCs).
   3. Run the downloaded file and complete the installation.
   4. Reopen Windows Security → Virus & threat protection → Virus & threat protection updates and confirm the Security intelligence version and Last updated are now current.
4. Use the MpCmdRun command-line utility (advanced manual update)
   1. Open Start, type cmd.
   2. Right‑click Command Prompt and select Run as administrator.
   3. In the elevated Command Prompt, run:

            "cd %ProgramData%\Microsoft\Windows Defender\Platform\" & for /f "delims=" %i in ('dir /b /ad-h /od') do set "mpdir=%i" & cd "%ProgramData%\Microsoft\Windows Defender\Platform\%mpdir%"
            MpCmdRun.exe -SignatureUpdate
      

      This uses the latest Defender platform folder and forces a signature (definitions) update.
   4. If that fails, try forcing from Microsoft Malware Protection Center (MMPC):

            MpCmdRun.exe -SignatureUpdate -MMPC
      

5. If updates still do not move past 2023 Work through these checks, which are common causes when Defender definitions never update:
   1. Confirm Defender is the active antivirus
      • If another antivirus is installed and registered with Windows Security Center, Microsoft Defender Antivirus is disabled and will not update. Uninstall or disable the third‑party AV if Defender is intended to be primary, then retry steps 2–4.
   2. Check network/update source configuration
      • If the device uses WSUS or a file share as the update source and those are stale, Defender will stay on old definitions.
      • If managed by an organization, contact the admin to ensure Defender security intelligence (KB2267602) is approved and current on WSUS or that the UNC share is updated.
   3. Try manual install again after verifying internet access
      • Ensure normal web browsing works and that security sites like https://www.microsoft.com/wdsi/definitions are reachable.

If the manual package install and MpCmdRun methods both work but automatic updates remain stuck, the issue is likely with the configured update source (WSUS, file share, or Windows Update service) and should be corrected there.

References:

• Troubleshoot Microsoft Defender Antivirus Security intelligence not getting updated
• Microsoft Defender Antivirus in the Windows Security app
• Microsoft Defender Antivirus security intelligence and product updates and support
• Antivirus and antimalware software: FAQ