Here's what's new in Serv-U 15.5.4 Hotfix 1. You can find the applicable system requirements here.

To view release notes, system requirements, and product guide PDFs for supported versions of Serv-U, see Serv-U previous versions. To view release notes for multiple versions and multiple SolarWinds Platform products on a single page, see the release notes aggregator.

Attention Serv-U customers

Serv-U 15.5.4 Hotfix 1 provides bugfixes related to CVE-2026-28318. For information about the 15.5.4 release, including EOL notices and upgrade information, see the Serv-U 15.5.4 release notes.

Customers who downloaded and installed Serv-U 15.5.4 should also download and install Serv-U 15.5.4 Hotfix 1.

New features and improvements in Serv-U

There were no features or improvements added for Serv-U in this release.

Fixed CVEs

At SolarWinds, we prioritize the swift resolution of CVEs to ensure the security and integrity of our software. In this release, we have successfully addressed the following CVEs.

Installation instructions

As you install this hotfix, take note of the files you add, remove, replace, or modify for your future reference should you decide to uninstall this hotfix at any point.

1. Shut down all running Serv-U processes.

   1. Right-click the tray icon and select Stop Serv-U.

   2. Right-click the tray icon and select Exit Tray.

2. Back up the following files:
   

   Windows OS

   • <Serv-U-InstallDir>\Serv-U.exe

   • <Serv-U-InstallDir>\Serv-U-Tray.exe

   • <Serv-U-InstallDir>\Serv-U.dll

   • <Serv-U-InstallDir>\Serv-U-RES.dll

   • <Serv-U-InstallDir>\RhinoNET.dll

   • <Serv-U-InstallDir>\RhinoRES.dll

   • <Serv-U-InstallDir>\Strings\Serv-U.str

   • <Serv-U-InstallDir>\Strings\Serv-U-Strings.h

    

   Linux OS:

   • <Serv-U-InstallDir>/Serv-U

   • <Serv-U-InstallDir>/Strings/Serv-U.str

   • <Serv-U-InstallDir>/Strings/Serv-U-Strings.h

3. Extract the hotfix archive to a temporary location.

4. Open the folder for the platform on which Serv-U is installed.
   For example, open the Linux/64-bit folder if Serv-U is installed on a 64-bit version of Linux.

5. On Linux, modify the permissions of the file by executing the following command:
   
   chmod u+xs Serv-U

6. Copy the contents of this folder to your Serv-U installation directory.

7. Start the Serv-U Tray application.

8. Right-click the Serv-U Tray icon and select Start Serv-U.
   The hotfix is installed.

Result

An attacker can no longer crash the Serv-U service by sending a simple request to the server with Content-Encoding: deflate and some data.

Uninstallation instructions

1. Shut down all running Serv-U processes.

   1. Right-click the tray icon and select Stop Serv-U.

   2. Right-click the tray icon and select Exit Tray.

2. Replace the following files with the ones you backed up during installation:
   

   Windows OS

   • <Serv-U-InstallDir>\Serv-U.exe

   • <Serv-U-InstallDir>\Serv-U-Tray.exe

   • <Serv-U-InstallDir>\Serv-U.dll

   • <Serv-U-InstallDir>\Serv-U-RES.dll

   • <Serv-U-InstallDir>\RhinoNET.dll

   • <Serv-U-InstallDir>\RhinoRES.dll

   • <Serv-U-InstallDir>\Strings\Serv-U.str

   • <Serv-U-InstallDir>\Strings\Serv-U-Strings.h

    

   Linux OS:

   • <Serv-U-InstallDir>/Serv-U

   • <Serv-U-InstallDir>/Strings/Serv-U.str

   • <Serv-U-InstallDir>/Strings/Serv-U-Strings.h

3. Start the Serv-U Tray application.

4. Right-click the Serv-U Tray icon and select Start Serv-U.
   The hotfix is uninstalled.

For more information, contact Technical Support at https://customerportal.solarwinds.com/support/submit-a-ticket.

End of life

See the End of Life Policy for information about SolarWinds product life cycle phases. To see EoL dates for earlier Serv-U versions, see Serv-U release history.

Legal notices

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