InstallBuilder AutoUpdate tool and regular installers enabling <checkForUpdates> built with versions earlier than 19.11 are vulnerable to Billion laughs attack (denial-of-service).

Under certain circumstances, when manipulating the Windows registry, InstallBuilder uses the reg.exe system command. The full path to the command is not enforced, which results in a search in the search path until a binary can be identified. This makes the installer/uninstaller vulnerable to Path Interception by Search Order Hijacking, potentially allowing an attacker to plant a malicious reg.exe command so it takes precedence over the system command. The vulnerability only affects Windows installers.

On Windows, the uninstaller binary copies itself to a fixed temporary location, which is then executed (the originally called uninstaller exits, so it does not block the installation directory). This temporary location is not randomized and does not restrict access to Administrators only so a potential attacker could plant a binary to replace the copied binary right before it gets called, thus gaining Administrator privileges (if the original uninstaller was executed as Administrator). The vulnerability only affects Windows installers.