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Turn on 64-bit tab processes when running in Enhanced Protected Mode on 64-bit versions of Windows

This policy determines whether Internet Explorer 11 uses 64-bit or 32-bit tab processes while running in Enhanced Protected Mode on 64-bit versions of Windows.

since 0.9.8.11

Purpose

Show registry keys (2)
  • HKLM\Software\Policies\Microsoft\Internet Explorer\Main\Isolation64Bit
  • HKCU\Software\Policies\Microsoft\Internet Explorer\Main\Isolation64Bit

This policy determines whether Internet Explorer 11 uses 64-bit or 32-bit tab processes while running in Enhanced Protected Mode on 64-bit versions of Windows.

When the policy is enabled, affected tabs run in 64-bit processes. When it is disabled, Internet Explorer uses 32-bit tab processes. If the policy is not configured, users can control the corresponding Internet Explorer setting.

Notes

Security

Microsoft identifies improved resistance to attacks that exploit memory-safety vulnerabilities as a security benefit of 64-bit tab processes. This policy does not enable Enhanced Protected Mode or Protected Mode by itself. Its security effect therefore depends on Enhanced Protected Mode being active, which in turn applies to security zones for which Protected Mode is enabled.

Using 32-bit tab processes provides greater compatibility but does not provide the additional protection associated with 64-bit processes against certain memory-based attacks.

Possible side effects

Some ActiveX controls and toolbars might not be available as 64-bit components and therefore cannot be loaded or used by 64-bit tab processes. Applications and websites that depend on such 32-bit extensions might lose functionality.

Notes

This policy applies to Internet Explorer 11 on 64-bit versions of Windows and has an effect only when Enhanced Protected Mode is active. The Isolation64Bit registry value is distinct from the separate Isolation value that controls Enhanced Protected Mode.

The Internet Explorer 11 desktop application has been retired and permanently disabled on certain Windows versions. Microsoft Edge in Internet Explorer mode continues to use the Internet Explorer 11 MSHTML engine and supports Internet Explorer policies that affect security zones and Protected Mode.

Microsoft documentation

Microsoft Learn: New group policy settings for Internet Explorer 11

Microsoft Learn: InternetExplorer Policy CSP

See also