Nullsoft Scriptable Install System (NSIS) before 2.49 has unsafe implicit linking against Version.dll. In other words, there is no protection mechanism in which a wrapper function resolves the dependency at an appropriate time during runtime.

Nullsoft Scriptable Install System (NSIS) before 2.49 uses temporary folder locations that allow unprivileged local users to overwrite files. This allows a local attack in which either a plugin or the uninstaller can be replaced by a Trojan horse program.