WinFsp 2026 Beta4

CHANGES SINCE WINFSP 2025

• [FIX] Fixes vulnerability CVE-2026-3006 reported by Tay Kiat Loong (GitHub: @Owl4444).

• [FIX] Fixes vulnerability CVE-2026-7162 reported by Tay Kiat Loong (GitHub: @Owl4444) and uhg (GitHub: @UltimateHG).

• [FIX] Fixes vulnerability reported by Wencheng Xue.

• [FIX] Fixes vulnerability reported by Abhinav Agarwal (GitHub @abhinavagarwal07).

• [FIX] Fixes deadlock during cached writes under memory pressure. See PR #677 for discussion.

• [FIX] Fixes deadlock in the file system notification mechanism with concurrent renames. See fix PR #669 by @yeonsh and test PR #672 by @Maksim-Isakau.

• [FIX] Fixes deadlock when closing named streams while the file system is being forcibly terminated. See issue #680.

• [FIX] Fixes another complicated deadlock when the file system is being forcibly terminated. See issue #682.

• [FIX] The WinFsp Network Provider provides improved shell support for network file systems not managed by the Launcher. See commit f021496.

• [FIX] Fixes a problem with mounting on a directory with a trailing backslash. See issue #674.

• [FUSE] Add FUSE option FlushOnCleanup. See PR #614 by @chenjie4255.

• [FUSE] FUSE now respects the direct_io flag. See PR #646 by @chenjie4255.

• [FUSE] Add FUSE option AddWriteEaAccess. See PR #648 by @chenjie4255.

BUILD HASHES (SHA256)

• winfsp-2.2.26215.msi: 2ECB5C89405488A95BBD8A01875E02C48534FD37BBDFD84488F7590464D65944
• winfsp-tests-2.2.26215.zip: B91166DC67075A3F784274AF43E2C5D015C36E57C598CA74DF64467FC97106E5

WinFsp 2026 Beta3

CHANGES SINCE WINFSP 2025

• [FIX] Fixes vulnerability CVE-2026-3006 discovered by Tay Kiat Loong (GitHub: @Owl4444).

• [FIX] Fixes vulnerability CVE-2026-7162 discovered by Tay Kiat Loong (GitHub: @Owl4444) and uhg (GitHub: @UltimateHG).

• [FIX] Fixes deadlock during cached writes under memory pressure. See PR #677 for discussion.

• [FIX] Fixes deadlock in the file system notification mechanism with concurrent renames. See fix PR #669 by @yeonsh and test PR #672 by @Maksim-Isakau.

• [FIX] The WinFsp Network Provider provides improved shell support for network file systems not managed by the Launcher. See commit f021496.

• [FUSE] Add FUSE option FlushOnCleanup. See PR #614 by @chenjie4255.

• [FUSE] FUSE now respects the direct_io flag. See PR #646 by @chenjie4255.

• [FUSE] Add FUSE option AddWriteEaAccess. See PR #648 by @chenjie4255.

BUILD HASHES (SHA256)

• winfsp-2.2.26194.msi: 7B41020618CDCC33D699D0E15C1DF660F0762A09B57080049C565857AC00BD9D
• winfsp-tests-2.2.26194.zip: 3626830EE6807E9C4F812C08076497A6BA65391DE4BB3F66FEC298E2858A74FF

WinFsp 2026 Beta2

CHANGES SINCE WINFSP 2025

• [FIX] Fixes vulnerability CVE-2026-3006 discovered by Tay Kiat Loong (GitHub: @Owl4444).

• [FIX] Fixes vulnerability CVE-2026-7162 discovered by Tay Kiat Loong (GitHub: @Owl4444) and uhg (GitHub: @UltimateHG).

• [FIX] Fixes deadlock in the file system notification mechanism with concurrent renames. See fix PR #669 by @yeonsh and test PR #672 by @Maksim-Isakau.

• [FIX] The WinFsp Network Provider provides improved shell support for network file systems not managed by the Launcher. See commit f021496.

• [FUSE] Add FUSE option FlushOnCleanup. See PR #614 by @chenjie4255.

• [FUSE] FUSE now respects the direct_io flag. See PR #646 by @chenjie4255.

• [FUSE] Add FUSE option AddWriteEaAccess. See PR #648 by @chenjie4255.

BUILD HASHES (SHA256)

• winfsp-2.2.26183.msi: C86E0D9281241C716210249EC0E8752E2698C7610113162782A6EF866FF86432
• winfsp-tests-2.2.26183.zip: B7712C68599673BC8D7E6906194C55F0EC6CA369B6694366206D3EB9DA0BCAEC

WinFsp 2026 Beta1

CHANGES SINCE WINFSP 2025

• [FIX] Fixes vulnerability CVE-2026-3006 discovered by Tay Kiat Loong. PLEASE UPGRADE!

• [FIX] The WinFsp Network Provider provides improved shell support for network file systems not managed by the Launcher. See commit f021496.

• [FUSE] Add FUSE option FlushOnCleanup. See PR #614 by @chenjie4255.

• [FUSE] FUSE now respects the direct_io flag. See PR #626 by @chenjie4255.

• [FUSE] Add FUSE option AddWriteEaAccess. See PR #648 by @chenjie4255.

BUILD HASHES (SHA256)

• winfsp-2.2.26112.msi: F9E70EDE2344A30D377A38555E2128C0770D64DDC53C0E2AF7DFE0C605F422A8
• winfsp-tests-2.2.26112.zip: 3AEF9DD925365352D7539EBB760431970C6861B0CC88940D796CAD4D800335EF

WinFsp 2025

CHANGES SINCE WINFSP 2023

• [FIX] Fixes a compatibility problem with certain AntiVirus products (e.g. Trend Micro).

• [FIX] Fixes a couple of rare BSODs on recent versions of Windows 11. See commits a482183, a2cd697 for details.

• [FIX] Fixes a rare problem when using NtCreateFile to perform relative opens on a network drive (see GitHub issue #561).

• [FIX] Fixes a racing issue with two processes competing to start the FSD discovered during testing.

BUILD HASHES (SHA256)

• winfsp-2.1.25156.msi: 073A70E00F77423E34BED98B86E600DEF93393BA5822204FAC57A29324DB9F7A
• winfsp-tests-2.1.25156.zip: 0CFC68791703C80F96C729EBD38B63187DE53E19BAA1C603A7059D6EA87C5F52

WinFsp 2024 Beta2

CHANGES SINCE WINFSP 2023

• [FIX] Fixes a rare BSOD on recent versions of Windows. See commit a482183 for details.

• [FIX] Fixes a rare problem when using NtCreateFile to perform relative opens on a network drive (see GitHub issue #561).

• [FIX] Fixes a racing issue with two processes competing to start the FSD discovered during testing.

BUILD HASHES (SHA256)

• winfsp-2.1.24255.msi: 5F05856A75E89C244A9D845E9A8B426052A33D26E65874277CE8871FEC7073D6
• winfsp-tests-2.1.24255.zip: 370EED8129CD6854C6278575F04C3B91D248E1CFA362DD795152EE10F005978C

WinFsp 2024 Beta1

CHANGES SINCE WINFSP 2023

• [FIX] Fixes a rare BSOD on recent versions of Windows. See commit a482183 for details.

• [FIX] Fixes a racing issue with two processes competing to start the FSD discovered during testing.

BUILD HASHES (SHA256)

• winfsp-2.1.24051.msi: 1A9C5122C53EE376CDCF9A69F9B0C5D3B297A499105ACC39A50C704F8E80268E
• winfsp-tests-2.1.24051.zip: 6438C4A7C14AEC2C010EB1EA52C84C4232DD12A9B68763E3EBE6D1134147E903

WinFsp 2023

CHANGES SINCE WINFSP 2022.2

This release is a major version change for WinFsp (from 1.x to 2.x). There are no backwards incompatible API changes in this release, but nevertheless enough things change that warrant a version change.

The major new feature of this release is that it allows uninstallation and reinstallation of WinFsp without reboot. Going forward installers named winfsp-2.x.y.msi can be uninstalled and reinstalled without reboot. Furthermore a later version winfsp-2.x.y.msi installer can be used to upgrade over an earlier version winfsp-2.x.y.msi installer. However note that a winfsp-2.x.y.msi installer cannot be used to upgrade over a legacy winfsp-1.x.y.msi installer; you will still need to uninstall the old winfsp-1.x.y.msi installer, potentially reboot and then install the new winfsp-2.x.y.msi installer.

Changes visible to file system developers are listed below:

• WinFsp executable files are now installed by default in the directory C:\Program Files (x86)\WinFsp\SxS\sxs.<InstanceID>\bin. The previous directory C:\Program Files (x86)\WinFsp\bin is now a junction that points to the above directory.

• The WinFsp driver name is no longer winfsp, but rather a name such as winfsp+<InstanceID>. This means that managing the driver using the sc.exe utility is no longer as easy.

• The fsptool utility has been updated with new commands lsdrv, load, unload and ver. The lsdrv, load and unload commands can be used to manage the driver from the command line. This is rarely necessary, but may be useful for troubleshooting purposes.

• Prior to this release the WinFsp driver would never unmount a file system volume unless the user mode file system requested the unmount. From this release onward it is possible for the WinFsp driver to unmount a file system volume, without a user mode file system request. This is to allow for the driver to be unloaded.

  A new operation DispatcherStopped has been added to FSP_FILE_SYSTEM_INTERFACE, which is sent after the file system volume has been unmounted and the file system dispatcher has been stopped. This can happen because of a user mode file system request via FspFileSystemStopDispatcher or because of driver unload. The DispatcherStopped operation includes a Normally parameter, which is TRUE for normal file system shutdown via FspFileSystemStopDispatcher and FALSE otherwise.

  Native file systems that use the FspService infrastructure can use the FspFileSystemStopServiceIfNecessary API to handle the DispatcherStopped operation (see the MEMFS and NTPTFS samples). FUSE file systems get this functionality for free. .NET file systems that use the Service class infrastructure also get this functionality for free.

• WinFsp now offers a .NET library that targets .NET Framework 3.5 (as before) and one that targets .NET Standard 2.0. This is due to work by @Noire001 in PR #451.

  • There is now a winfsp.net nuget package at https://www.nuget.org/packages/winfsp.net

• FUSE now supports path components up to 255 characters long (previously it was 255 bytes). This is due to work by @zeho11 in PR #474.

  • The FUSE passthrough file systems have been updated to support long paths. This is also due to work by @zeho11.

• In some rare circumstances WinFsp file systems could report duplicate directory entries. This problem has been fixed. (GitHub issue #475.)

• The WinFsp symbols directory has been removed. If you are looking for WinFsp symbols you can find them at https://github.com/winfsp/winfsp.sym

BUILD HASHES (SHA256)

• winfsp-2.0.23075.msi: 6324DC81194A6A08F97B6AECA303CF5C2325C53EDE153BAE9FC4378F0838C101
• winfsp-tests-2.0.23075.zip: AEECDAC2BE9684C4FF9D977C41853B0DE9E065C230DBA755E86C3F8130BBC816

WinFsp 2023 RC1

CHANGES SINCE WINFSP 2022.2

This release is a major version change for WinFsp (from 1.x to 2.x). There are no backwards incompatible API changes in this release, but nevertheless enough things change that warrant a version change.

The major new feature of this release is that it allows uninstallation and reinstallation of WinFsp without reboot. Going forward installers named winfsp-2.x.y.msi can be uninstalled and reinstalled without reboot. Furthermore a later version winfsp-2.x.y.msi installer can be used to upgrade over an earlier version winfsp-2.x.y.msi installer. However note that a winfsp-2.x.y.msi installer cannot be used to upgrade over a legacy winfsp-1.x.y.msi installer; you will still need to uninstall the old winfsp-1.x.y.msi installer, potentially reboot and then install the new winfsp-2.x.y.msi installer.

Changes visible to file system developers are listed below:

• WinFsp executable files are now installed by default in the directory C:\Program Files (x86)\WinFsp\SxS\sxs.<InstanceID>\bin. The previous directory C:\Program Files (x86)\WinFsp\bin is now a junction that points to the above directory.

• The WinFsp driver name is no longer winfsp, but rather a name such as winfsp+<InstanceID>. This means that managing the driver using the sc.exe utility is no longer as easy.

• The fsptool utility has been updated with new commands lsdrv, load, unload and ver. The lsdrv, load and unload commands can be used to manage the driver from the command line. This is rarely necessary, but may be useful for troubleshooting purposes.

• Prior to this release the WinFsp driver would never unmount a file system volume unless the user mode file system requested the unmount. From this release onward it is possible for the WinFsp driver to unmount a file system volume, without a user mode file system request. This is to allow for the driver to be unloaded.

  A new operation DispatcherStopped has been added to FSP_FILE_SYSTEM_INTERFACE, which is sent after the file system volume has been unmounted and the file system dispatcher has been stopped. This can happen because of a user mode file system request via FspFileSystemStopDispatcher or because of driver unload. The DispatcherStopped operation includes a Normally parameter, which is TRUE for normal file system shutdown via FspFileSystemStopDispatcher and FALSE otherwise.

  Native file systems that use the FspService infrastructure can use the FspFileSystemStopServiceIfNecessary API to handle the DispatcherStopped operation (see the MEMFS and NTPTFS samples). FUSE file systems get this functionality for free. .NET file systems that use the Service class infrastructure also get this functionality for free.

• WinFsp now offers a .NET library that targets .NET Framework 3.5 (as before) and one that targets .NET Standard 2.0. This is due to work by @Noire001 in PR #451.

  • There is now a winfsp.net nuget package at https://www.nuget.org/packages/winfsp.net

• FUSE now supports path components up to 255 characters long (previously it was 255 bytes). This is due to work by @zeho11 in PR #474.

  • The FUSE passthrough file systems have been updated to support long paths. This is also due to work by @zeho11.

• In some rare circumstances WinFsp file systems could report duplicate directory entries. This problem has been fixed. (GitHub issue #475.)

• The WinFsp symbols directory has been removed. If you are looking for WinFsp symbols you can find them at https://github.com/winfsp/winfsp.sym

BUILD HASHES (SHA256)

• winfsp-2.0.23055.msi: 7AB21329F49B4C057FC7C66876D2B502734E37C9BB0AD360DE9E8B3B9170971F
• winfsp-tests-2.0.23055.zip: 74B39EF9B2BA8D96D69CB99AB786904EB83EB7DB38F245CDAED0E92755A42EBE

WinFsp 2023 Beta2

CHANGES SINCE WINFSP 2022.2

This release is a major version change for WinFsp (from 1.x to 2.x). There are no backwards incompatible API changes in this release, but nevertheless enough things change that warrant a version change.

The major new feature of this release is that it allows uninstallation and reinstallation of WinFsp without reboot. Going forward installers named winfsp-2.x.y.msi can be uninstalled and reinstalled without reboot. Furthermore a later version winfsp-2.x.y.msi installer can be used to upgrade over an earlier version winfsp-2.x.y.msi installer. However note that a winfsp-2.x.y.msi installer cannot be used to upgrade over a legacy winfsp-1.x.y.msi installer; you will still need to uninstall the old winfsp-1.x.y.msi installer, potentially reboot and then install the new winfsp-2.x.y.msi installer.

Changes visible to file system developers are listed below:

• WinFsp executable files are now installed by default in the directory C:\Program Files (x86)\WinFsp\SxS\sxs.<InstanceID>\bin. The previous directory C:\Program Files (x86)\WinFsp\bin is now a junction that points to the above directory.

• The WinFsp driver name is no longer winfsp, but rather a name such as winfsp+<InstanceID>. This means that managing the driver using the sc.exe utility is no longer as easy.

• The fsptool utility has been updated with new commands lsdrv, load, unload and ver. The lsdrv, load and unload commands can be used to manage the driver from the command line. This is rarely necessary, but may be useful for troubleshooting purposes.

• Prior to this release the WinFsp driver would never unmount a file system volume unless the user mode file system requested the unmount. From this release onward it is possible for the WinFsp driver to unmount a file system volume, without a user mode file system request. This is to allow for the driver to be unloaded.

  A new operation DispatcherStopped has been added to FSP_FILE_SYSTEM_INTERFACE, which is sent after the file system volume has been unmounted and the file system dispatcher has been stopped. This can happen because of a user mode file system request via FspFileSystemStopDispatcher or because of driver unload. The DispatcherStopped operation includes a Normally parameter, which is TRUE for normal file system shutdown via FspFileSystemStopDispatcher and FALSE otherwise.

  Native file systems that use the FspService infrastructure can use the FspFileSystemStopServiceIfNecessary API to handle the DispatcherStopped operation (see the MEMFS and NTPTFS samples). FUSE file systems get this functionality for free. .NET file systems that use the Service class infrastructure also get this functionality for free.

• WinFsp now offers a .NET library that targets .NET Framework 3.5 (as before) and one that targets .NET Standard 2.0. This is due to work by @Noire001 in PR #451.

  • There is now a winfsp.net nuget package at https://www.nuget.org/packages/winfsp.net

• FUSE now supports path components up to 255 characters long (previously it was 255 bytes). This is due to work by @zeho11 in PR #474.

  • The FUSE passthrough file systems have been updated to support long paths. This is also due to work by @zeho11.

• The WinFsp symbols directory has been removed. If you are looking for WinFsp symbols you can find them at https://github.com/winfsp/winfsp.sym

BUILD HASHES (SHA256)

• winfsp-2.0.23033.msi: BF3595765FF179B6664600B0065CD77C89823A3803C55CBD35EE4E014141F16C
• winfsp-tests-2.0.23033.zip: 4A5B1B4F7AC93C91C6A0ADF08DF3CB1BF60AC88DE7EB23470DF89670AAF79BF1