ChatterBot is a machine learning, conversational dialog engine for creating chat bots. Prior to 1.2.14, UbuntuCorpusTrainer.extract() uses a predictable home-rooted output directory (~/ubuntu_data/ubuntu_dialogs) with a check-then-create pattern followed by tar.extractall(path=self.data_path), allowing a local attacker who pre-plants a symlink at the predictable path to cause archive contents to be written through the symlink to an attacker-chosen directory. This issue is fixed in version 1.2.14.