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Improper Link Resolution Before File Access ('Link Following')


Severity High
Score 7.9/10


WiX toolset lets developers create installers for Windows Installer, the Windows installation engine. The custom action behind WiX's 'RemoveFolderEx' functionality could allow a standard user to delete protected directories. 'RemoveFolderEx' deletes an entire directory tree during installation or uninstallation. It does so by recursing every subdirectory starting at a specified directory and adding each subdirectory to the list of directories Windows Installer should delete. If the setup author instructed 'RemoveFolderEx' to delete a per-user folder from a per-machine installer, an attacker could create a directory junction in that per-user folder pointing to a per-machine, protected directory. Windows Installer, when executing the per-machine installer after approval by an administrator, would delete the target of the directory junction. This vulnerability affects Wix versions prior to 3.14.1, and 4.0.x prior to 4.0.5, and WixToolset.Util.wixext versions 4.0.x prior to 4.0.5.

  • LOW
  • HIGH
  • LOW
  • NONE
  • HIGH

CWE-59 - Improper Link Resolution Before File Access

'Improper link resolution before file access' occurs when software accesses a file resource but fails to verify that the file isn't a link or shortcut to another file. An attacker can potentially gain access to arbitrary files and from there the impact can vary, depending on the application, from sensitive data exposure to remote code execution.


Advisory Timeline

  • Published